Xu Lei, Li Pei-Ling, Lyu Zhao-Zheng, Shen Jie, Qu Fan-Ming, Liu Guang Tong, Lu Li
Topological superconductors have attracted increased research interest because they have been proposed to host non-abelian Ising Anyon Majorana zero modes, which can be used to construct fault-tolerant quantum computers. This paper mainly reviews the electrical transport methods for detecting the presence of Majorana zero modes. First, the basic concepts of topological superconductivity, Majorana zero modes and non-Abelian statistics are introduced, followed by a summary of various schemes for implementing topological superconductivity. Experimental methods for detecting topological superconductivity or Majorana zero modes using low-temperature transport methods, including electron tunneling spectroscopy, Coulomb blockade spectroscopy and non-local conductance detection, which are widely used in superconductor/nanowire hybrid systems, are then discussed. On the other hand, measurements of the (inverse) AC Josephson effect and current (energy) phase relationships are also reviewed to identify MZM in Josephson devices. Meanwhile, to deepen our understanding of MZM, the trivial mechanisms for interpreting the experimental data observed in the above experiments are provided. Finally, a brief summary and outlook of the electrical transport methods of Majorana zero modes are presented.
{"title":"Detecting Majorana zero mode with transport measurements","authors":"Xu Lei, Li Pei-Ling, Lyu Zhao-Zheng, Shen Jie, Qu Fan-Ming, Liu Guang Tong, Lu Li","doi":"10.7498/aps.72.20230951","DOIUrl":"https://doi.org/10.7498/aps.72.20230951","url":null,"abstract":"Topological superconductors have attracted increased research interest because they have been proposed to host non-abelian Ising Anyon Majorana zero modes, which can be used to construct fault-tolerant quantum computers. This paper mainly reviews the electrical transport methods for detecting the presence of Majorana zero modes. First, the basic concepts of topological superconductivity, Majorana zero modes and non-Abelian statistics are introduced, followed by a summary of various schemes for implementing topological superconductivity. Experimental methods for detecting topological superconductivity or Majorana zero modes using low-temperature transport methods, including electron tunneling spectroscopy, Coulomb blockade spectroscopy and non-local conductance detection, which are widely used in superconductor/nanowire hybrid systems, are then discussed. On the other hand, measurements of the (inverse) AC Josephson effect and current (energy) phase relationships are also reviewed to identify MZM in Josephson devices. Meanwhile, to deepen our understanding of MZM, the trivial mechanisms for interpreting the experimental data observed in the above experiments are provided. Finally, a brief summary and outlook of the electrical transport methods of Majorana zero modes are presented.","PeriodicalId":6995,"journal":{"name":"Acta Physica Sinica","volume":null,"pages":null},"PeriodicalIF":1.0,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76093361","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Luo Yu-Xuan, Cheng Yong-Zhi, Chen Fu, Luo Hui, Li Xiang-Cheng
In this paper, a dual passband filter with spoof surface plasmon polaritons (SSPPs) and interdigital capacitance structure loaded on a coplanar waveguide (CPW) is proposed. Firstly, the hourglass-shaped SSPP unit-cell structure and the interdigital capacitor structure are introduced on the coplanar waveguide transmission line to obtain high fractional bandwidth and low insertion loss passband characteristics. Then, a dual passband filter is formed by loading the interdigital capacitor loop resonator to excite the trapped waves. The simulation results show that the proposed dual passband filter has excellent upper sideband rejection and dual passband filtering performance. The fractional bandwidths of the two passbands of the design are 46.8% (1.49-2.40 GHz) and 15.1% (2.98-3.63 GHz), respectively, which can achieve more than -40 dB rejection in the range of 4.77-7.48 GHz. The upper and lower cutoff frequencies of the two passbands can be independently regulated by changing the structural parameters of the proposed filter. In order to gain a deeper understanding of the operating principle of the dual passband filter, the corresponding dispersion curves and electric field distribution, LC equivalent circuit analysis are given. Finally, the prototype of the designed filter is fabricated according to the optimized parameter values. The experimental results are in good agreement with the simulation ones, indicating that the proposed dual-passband filter is of great importance in microwave integrated circuit applications.
{"title":"Dual-band filter design based on hourglass-shaped spoof surface plasmon polaritons and interdigital capacitor structure","authors":"Luo Yu-Xuan, Cheng Yong-Zhi, Chen Fu, Luo Hui, Li Xiang-Cheng","doi":"10.7498/aps.72.20221984","DOIUrl":"https://doi.org/10.7498/aps.72.20221984","url":null,"abstract":"In this paper, a dual passband filter with spoof surface plasmon polaritons (SSPPs) and interdigital capacitance structure loaded on a coplanar waveguide (CPW) is proposed. Firstly, the hourglass-shaped SSPP unit-cell structure and the interdigital capacitor structure are introduced on the coplanar waveguide transmission line to obtain high fractional bandwidth and low insertion loss passband characteristics. Then, a dual passband filter is formed by loading the interdigital capacitor loop resonator to excite the trapped waves. The simulation results show that the proposed dual passband filter has excellent upper sideband rejection and dual passband filtering performance. The fractional bandwidths of the two passbands of the design are 46.8% (1.49-2.40 GHz) and 15.1% (2.98-3.63 GHz), respectively, which can achieve more than -40 dB rejection in the range of 4.77-7.48 GHz. The upper and lower cutoff frequencies of the two passbands can be independently regulated by changing the structural parameters of the proposed filter. In order to gain a deeper understanding of the operating principle of the dual passband filter, the corresponding dispersion curves and electric field distribution, LC equivalent circuit analysis are given. Finally, the prototype of the designed filter is fabricated according to the optimized parameter values. The experimental results are in good agreement with the simulation ones, indicating that the proposed dual-passband filter is of great importance in microwave integrated circuit applications.","PeriodicalId":6995,"journal":{"name":"Acta Physica Sinica","volume":null,"pages":null},"PeriodicalIF":1.0,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87867105","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Wang Jing Jiao Yang Tian Wen-De Chen Kang, 焦阳, 田文得, 陈康
Active matter refers to a class of substances capable of autonomously moving by harnessing energy from their surrounding environment. These substances exhibit unique non-equilibrium phenomena, and hence have attracted great attention in the scientific community. Many active matters, such as bacteria, cells, micro-swimmers, and self-propelled colloidal particles, operate in viscous environment and their motions are usually described using overdamped models. Examples include overdamped active Brownian particle (ABP) model for self-propelled colloidal particles in solution and run-and-tumble (RTP) model for swimming bacteria. In recent years, increasing research studies have focused on the impact of inertia on the behavior of active matter. Vibrating robots, runners, flying insects, and micro-fliers are example active systems in the underdamped condition. The motion of these active matters can be modelled by underdamped Langevin equation, known as the active inertial particle (AIP) model. Previous studies have demonstrated that, similar to ABP systems, motility-induced phase separation (MIPS) phenomena also happen in AIP systems under certain density conditions. However, due to the strong collision-and-rebound effect, aggregation of AIP particles and hence the MIPS are impeded. In complex living/application environments, mixture of different active agents is often seen. Some studies on mixed systems of active matter show that the composition is an important quantity, influencing the phase separation phenomena. In this paper, we study the phase separation phenomena in mixed systems composed of low- and high-inertia active particles by underdamped Langevin dynamics simulations. We find that, compared to single-component system, the mixed systems are unexpectedly more favorable for the occurrence of phase separation at moderate overall concentration and certain range of component fraction, while more unfavorable for phase separation at high overall concentration. The underlying mechanism is that the presence of a small amount of the high-inertia particles could accelerate the motion of the low-inertia particles, and hence facilitate their aggregation and promote the phase separation. However, when the fraction of the high-inertia particles is large, frequent elastic collisions would disturb the aggregation of the low-inertia particles and suppress the occurrence of phase separation. Our results provide new sights into the collective behavior of active materials and also a reference for their design and applications.
{"title":"Phase separation in mixed systems of active particles with low and high inertia","authors":"Wang Jing Jiao Yang Tian Wen-De Chen Kang, 焦阳, 田文得, 陈康","doi":"10.7498/aps.72.20230792","DOIUrl":"https://doi.org/10.7498/aps.72.20230792","url":null,"abstract":"Active matter refers to a class of substances capable of autonomously moving by harnessing energy from their surrounding environment. These substances exhibit unique non-equilibrium phenomena, and hence have attracted great attention in the scientific community. Many active matters, such as bacteria, cells, micro-swimmers, and self-propelled colloidal particles, operate in viscous environment and their motions are usually described using overdamped models. Examples include overdamped active Brownian particle (ABP) model for self-propelled colloidal particles in solution and run-and-tumble (RTP) model for swimming bacteria. In recent years, increasing research studies have focused on the impact of inertia on the behavior of active matter. Vibrating robots, runners, flying insects, and micro-fliers are example active systems in the underdamped condition. The motion of these active matters can be modelled by underdamped Langevin equation, known as the active inertial particle (AIP) model. Previous studies have demonstrated that, similar to ABP systems, motility-induced phase separation (MIPS) phenomena also happen in AIP systems under certain density conditions. However, due to the strong collision-and-rebound effect, aggregation of AIP particles and hence the MIPS are impeded. In complex living/application environments, mixture of different active agents is often seen. Some studies on mixed systems of active matter show that the composition is an important quantity, influencing the phase separation phenomena. In this paper, we study the phase separation phenomena in mixed systems composed of low- and high-inertia active particles by underdamped Langevin dynamics simulations. We find that, compared to single-component system, the mixed systems are unexpectedly more favorable for the occurrence of phase separation at moderate overall concentration and certain range of component fraction, while more unfavorable for phase separation at high overall concentration. The underlying mechanism is that the presence of a small amount of the high-inertia particles could accelerate the motion of the low-inertia particles, and hence facilitate their aggregation and promote the phase separation. However, when the fraction of the high-inertia particles is large, frequent elastic collisions would disturb the aggregation of the low-inertia particles and suppress the occurrence of phase separation. Our results provide new sights into the collective behavior of active materials and also a reference for their design and applications.","PeriodicalId":6995,"journal":{"name":"Acta Physica Sinica","volume":null,"pages":null},"PeriodicalIF":1.0,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86842477","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
By combining plane waves with Gaussian or spline functions, this paper constructs a new composite basis set. As a non local basis vector, the plane wave basis group needs a large number of plane waves to expand all parts of the physical space, including the intermediate regions that are not important to our problems. Our basis set uses the local characteristics of Gaussian function or spline function at the same time, and controls the energy interval by selecting different plane wave vectors, so as to realize the partition solution of Hamiltonian matrix. Orthogonal normalization of composite basis sets is performed using Gram-Schmidt's orthogonalization method or Löwdin's orthogonalization method. Considering the completeness of plane wave vector, a certain value of positive and negative should be selected at the same time. Here, by changing the absolute value of wave vector, we can select the eigenvalue interval to be solved. The plane wave with a specific wave vector value is equivalent to a trial solution in the region with gentle potential energy. The algorithm automatically combines local Gaussian or spline functions to match the wave vector value difference between the trial solution and the strict solution. By selecting the absolute value of the wave vector in the plane wave function, this paper turns the calculation of large Hamiltonian matrices into the calculation of multiple small matrices, together with reducing the basis numbers in the region where the electron potential changes smoothly, we can significantly reduce the computational time. As an example, we apply this basis set to a one-dimensional finite depth potential well, it can be found that our method significantly reduce the number of basis vectors used to expand the wave function while maintaining a suitable degree of computational accuracy. We also studied the impact of different parameters on calculation accuracy. Finally, the above calculation method can be directly applied to the DFT calculation of plasmons in silver nanoplates or other metal nanostructures. Given a reasonable tentative initial state, the ground state electron density distribution of the system can be solved by self consistent solution using DFT theory, and then the electromagnetic field distribution and optical properties of the system can be solved using time-dependent density functional theory theory (TDDFT).
{"title":"Composite Basis Set of Plane Wave and Gaussian Function or Spline Function","authors":"Zhang Guang-Di, Mao Li, Xu Hong-Xing","doi":"10.7498/aps.72.20230872","DOIUrl":"https://doi.org/10.7498/aps.72.20230872","url":null,"abstract":"By combining plane waves with Gaussian or spline functions, this paper constructs a new composite basis set. As a non local basis vector, the plane wave basis group needs a large number of plane waves to expand all parts of the physical space, including the intermediate regions that are not important to our problems. Our basis set uses the local characteristics of Gaussian function or spline function at the same time, and controls the energy interval by selecting different plane wave vectors, so as to realize the partition solution of Hamiltonian matrix. Orthogonal normalization of composite basis sets is performed using Gram-Schmidt's orthogonalization method or Löwdin's orthogonalization method. Considering the completeness of plane wave vector, a certain value of positive and negative should be selected at the same time. Here, by changing the absolute value of wave vector, we can select the eigenvalue interval to be solved. The plane wave with a specific wave vector value is equivalent to a trial solution in the region with gentle potential energy. The algorithm automatically combines local Gaussian or spline functions to match the wave vector value difference between the trial solution and the strict solution. By selecting the absolute value of the wave vector in the plane wave function, this paper turns the calculation of large Hamiltonian matrices into the calculation of multiple small matrices, together with reducing the basis numbers in the region where the electron potential changes smoothly, we can significantly reduce the computational time. As an example, we apply this basis set to a one-dimensional finite depth potential well, it can be found that our method significantly reduce the number of basis vectors used to expand the wave function while maintaining a suitable degree of computational accuracy. We also studied the impact of different parameters on calculation accuracy. Finally, the above calculation method can be directly applied to the DFT calculation of plasmons in silver nanoplates or other metal nanostructures. Given a reasonable tentative initial state, the ground state electron density distribution of the system can be solved by self consistent solution using DFT theory, and then the electromagnetic field distribution and optical properties of the system can be solved using time-dependent density functional theory theory (TDDFT).","PeriodicalId":6995,"journal":{"name":"Acta Physica Sinica","volume":null,"pages":null},"PeriodicalIF":1.0,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86919790","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Chenrui Zhao, Yunxin Wei, Tingting Liu, and Minghui Qin
Ferrimagnetic domain walls are attracting more and more attentions due to their interesting physics and potential applications in future spintronic devices, particularly attributes to the non-zero net magnetization and ultrafast dynamic properties. Exploring effective methods for driving domain walls with low energy consumption and high efficiency does provide important information for experimental design and device development. In this work, we study theoretically and numerically the dynamics of ferrimagnetic domain wall driven by the sinusoidal microwave magnetic field using the collective coordinate theory and Landau-Lifshitz-Gilbert simulations of atomistic spin model. It is revealed that the microwave field can drive the propagation of the domain wall along nanowires when the frequency falls into appropriate regions, which allows one to modulate the domain wall dynamics through tuning field frequency. Specifically, the domain wall velocity is proportional to the field frequency and the net angular momentum below the critical frequency, while it quickly decreases to zero above the critical frequency. The physical mechanisms of the results are discussed in detail, and the influences of the biaxial anisotropy and other parameters on the velocity of domain wall are explored. Thus, it is suggested that the domain wall dynamics can be effectively regulated by adjusting the basic magnetic structure and magnetic anisotropic, in addition to the external microwave field frequency. This work uncovers interesint dynamics of ferrimagnetic domain wall driven by sinusoidal microwave magnetic field, which is helpful for domain wall-based spintronic device design.
{"title":"Domain wall dynamics driven by sinusoidal polarized magnetic field in ferrimagnets","authors":"Chenrui Zhao, Yunxin Wei, Tingting Liu, and Minghui Qin","doi":"10.7498/aps.72.20230913","DOIUrl":"https://doi.org/10.7498/aps.72.20230913","url":null,"abstract":"Ferrimagnetic domain walls are attracting more and more attentions due to their interesting physics and potential applications in future spintronic devices, particularly attributes to the non-zero net magnetization and ultrafast dynamic properties. Exploring effective methods for driving domain walls with low energy consumption and high efficiency does provide important information for experimental design and device development. In this work, we study theoretically and numerically the dynamics of ferrimagnetic domain wall driven by the sinusoidal microwave magnetic field using the collective coordinate theory and Landau-Lifshitz-Gilbert simulations of atomistic spin model. It is revealed that the microwave field can drive the propagation of the domain wall along nanowires when the frequency falls into appropriate regions, which allows one to modulate the domain wall dynamics through tuning field frequency. Specifically, the domain wall velocity is proportional to the field frequency and the net angular momentum below the critical frequency, while it quickly decreases to zero above the critical frequency. The physical mechanisms of the results are discussed in detail, and the influences of the biaxial anisotropy and other parameters on the velocity of domain wall are explored. Thus, it is suggested that the domain wall dynamics can be effectively regulated by adjusting the basic magnetic structure and magnetic anisotropic, in addition to the external microwave field frequency. This work uncovers interesint dynamics of ferrimagnetic domain wall driven by sinusoidal microwave magnetic field, which is helpful for domain wall-based spintronic device design.","PeriodicalId":6995,"journal":{"name":"Acta Physica Sinica","volume":null,"pages":null},"PeriodicalIF":1.0,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87088658","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Dan Min, 金凡亚, Chen Lun-Jiang, He Yan-Bin, Wan Jun-Hao, Zhang Hong, Zhang Ke-Jia, Yang Yin, Jin Fan-Ya
In order to further improve the superconducting current carrying capacity of REBCO coated conductor under strong magnetic field, ion irradiation is used to generate the pinning center of introduced magnetic flux in the REBCO coated conductor. In this paper, the H-ion irradiation of REBCO second generation high temperature superconductor strip was carried out by using the 320kV high charge state ion synthesis research platform. DB-SPBA combined with Raman spectroscopy was used to measure the change of microstructure in YBCO samples irradiated by H+ions within the range of 5.0×1014~1.0×1016. The positron annihilation parameters in YBCO before and after irradiation were analyzed. It is found that after 100 keV H+ion irradiation, a large number of defects including vacancy, vacancy group or dislocation group are produced in the superconducting layer. The larger the irradiation dose, the more vacancy type defects are produced, the more complex the defect types are, and the annihilation mechanism of positrons in the defects changes. Raman spectroscopy results show that with the increase of H+ion irradiation dose, the oxygen atoms in the coating rearrange, the plane spacing increases, the orthogonal phase structure of the coating is destroyed, and the degree of order decreases. The defects produced by such ion irradiation lay a foundation for the introduction of flux pinning centers. Further research can be carried out in combination with X-ray diffractometer, transmission electron microscope, superconductivity and other testing methods to provide theoretical and practical reference for the optimization of material properties.
{"title":"Defect Evolution in Y0.5Gd0.5Ba2Cu3O7-δ Layer by H Ion Irradiation","authors":"Dan Min, 金凡亚, Chen Lun-Jiang, He Yan-Bin, Wan Jun-Hao, Zhang Hong, Zhang Ke-Jia, Yang Yin, Jin Fan-Ya","doi":"10.7498/aps.72.20221612","DOIUrl":"https://doi.org/10.7498/aps.72.20221612","url":null,"abstract":"In order to further improve the superconducting current carrying capacity of REBCO coated conductor under strong magnetic field, ion irradiation is used to generate the pinning center of introduced magnetic flux in the REBCO coated conductor. In this paper, the H-ion irradiation of REBCO second generation high temperature superconductor strip was carried out by using the 320kV high charge state ion synthesis research platform. DB-SPBA combined with Raman spectroscopy was used to measure the change of microstructure in YBCO samples irradiated by H+ions within the range of 5.0×1014~1.0×1016. The positron annihilation parameters in YBCO before and after irradiation were analyzed. It is found that after 100 keV H+ion irradiation, a large number of defects including vacancy, vacancy group or dislocation group are produced in the superconducting layer. The larger the irradiation dose, the more vacancy type defects are produced, the more complex the defect types are, and the annihilation mechanism of positrons in the defects changes. Raman spectroscopy results show that with the increase of H+ion irradiation dose, the oxygen atoms in the coating rearrange, the plane spacing increases, the orthogonal phase structure of the coating is destroyed, and the degree of order decreases. The defects produced by such ion irradiation lay a foundation for the introduction of flux pinning centers. Further research can be carried out in combination with X-ray diffractometer, transmission electron microscope, superconductivity and other testing methods to provide theoretical and practical reference for the optimization of material properties.","PeriodicalId":6995,"journal":{"name":"Acta Physica Sinica","volume":null,"pages":null},"PeriodicalIF":1.0,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87584065","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Liu Huizhen, Liu Bei, Dong Jiabin, Li Jianpeng, Cao Zixiu, Liu Yue, Meng Rutao, Zhang Yi
Efficient copper based thin film solar cells usually use inorganic n-type semiconductor material CdS as the buffer layer. Therefore, the interface quality and energy band matching between the buffer layer and the absorption layer are crucial to the collection and utilization of carriers. Heat treatment can promote the mutual diffusion of interface elements, the migration of ions in the material and the change of defect state, and the proper temperature will change the degree of Cu-Zn ordering in the absorption layer, so as to improve the efficiency of the solar cells. Based on the optimization of CdS basic process, the strategy of annealing CdS/copper-based thin film heterojunction in sulfur atmosphere further improves the quality of CdS thin film, and applies it to copper-based solar cells to regulate the p-n heterojunction energy band gap matching of copper-based thin film cells. The results show that the annealing of CdS film in sulfur-containing inert atmosphere can effectively improve the crystal quality of CdS film and inhibit the non-radiative recombination loss caused by defect trapping at the interface of CZTS/CdS heterojunction, and the open-circuit voltage of the device can be significantly increased, up to 718 mV. In addition, annealing CZTS/CdS heterojunction in S/Ar atmosphere can effectively improve the p-n heterojunction energy band gap matching, which not only improves the electron transmission, but also reduces the carrier recombination, thus improving the Voc and FF of devices. Besides, the oxygen element in CdS film can be replaced by sulfur element in sulfur atmosphere to improve the quality of CdS film and thus enhance the short-wave absorption of solar cell devices. Therefore, In terms of device efficiency, the efficiency of CZTS solar cell based on sputtering method has increased from 3.47% to 5.68%, which is about twice that of non-annealing treatment, Its device structure is Glass/Mo/CZTS/CdS/i-ZnO/Al:ZnO/Ni/Al, providing a reliable process window for copper based thin film solar cell devices to achieve high open-circuit voltage. Meanwhile, this study strongly demonstrates the importance of annealing atmosphere selection for CdS quality and energy band matching of CZTS/CdS heterojunction. In addition to interface interdiffusion, the composition and crystallinity of thin film materials are controlled.
{"title":"Study on the regulation of solar cell performance by cadmium sulfide/copper-based thin film heterojunction annealing under different atmospheres","authors":"Liu Huizhen, Liu Bei, Dong Jiabin, Li Jianpeng, Cao Zixiu, Liu Yue, Meng Rutao, Zhang Yi","doi":"10.7498/aps.72.20230105","DOIUrl":"https://doi.org/10.7498/aps.72.20230105","url":null,"abstract":"Efficient copper based thin film solar cells usually use inorganic n-type semiconductor material CdS as the buffer layer. Therefore, the interface quality and energy band matching between the buffer layer and the absorption layer are crucial to the collection and utilization of carriers. Heat treatment can promote the mutual diffusion of interface elements, the migration of ions in the material and the change of defect state, and the proper temperature will change the degree of Cu-Zn ordering in the absorption layer, so as to improve the efficiency of the solar cells. Based on the optimization of CdS basic process, the strategy of annealing CdS/copper-based thin film heterojunction in sulfur atmosphere further improves the quality of CdS thin film, and applies it to copper-based solar cells to regulate the p-n heterojunction energy band gap matching of copper-based thin film cells. The results show that the annealing of CdS film in sulfur-containing inert atmosphere can effectively improve the crystal quality of CdS film and inhibit the non-radiative recombination loss caused by defect trapping at the interface of CZTS/CdS heterojunction, and the open-circuit voltage of the device can be significantly increased, up to 718 mV. In addition, annealing CZTS/CdS heterojunction in S/Ar atmosphere can effectively improve the p-n heterojunction energy band gap matching, which not only improves the electron transmission, but also reduces the carrier recombination, thus improving the Voc and FF of devices. Besides, the oxygen element in CdS film can be replaced by sulfur element in sulfur atmosphere to improve the quality of CdS film and thus enhance the short-wave absorption of solar cell devices. Therefore, In terms of device efficiency, the efficiency of CZTS solar cell based on sputtering method has increased from 3.47% to 5.68%, which is about twice that of non-annealing treatment, Its device structure is Glass/Mo/CZTS/CdS/i-ZnO/Al:ZnO/Ni/Al, providing a reliable process window for copper based thin film solar cell devices to achieve high open-circuit voltage. Meanwhile, this study strongly demonstrates the importance of annealing atmosphere selection for CdS quality and energy band matching of CZTS/CdS heterojunction. In addition to interface interdiffusion, the composition and crystallinity of thin film materials are controlled.","PeriodicalId":6995,"journal":{"name":"Acta Physica Sinica","volume":null,"pages":null},"PeriodicalIF":1.0,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88107704","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Keda Liang, Tengfei Liu, Zhe Chang, Meng Zhang, ZhiXin Li, Songsong Huang, Jing Wang
The propagation speed is one of the important parameters of the internal solitary waves(ISWs). How to obtain the ISWs speed through optical remote sensing images accurately and quickly is an important problem to be solved. In this paper, we simulate ISWs optical remote sensing imaging and obtain an experimental database and build the ISWs speed inversion models based on a single-scene optical remote sensing image by using the least squares method and the support vector machine. The accuracy of the ISW speed inversion models were tested by using MODIS Image and GF-4 image data of the South China Sea. The study results show that: The least squares ISW speed inversion model can give the regression equation, which is more intuitive and has less accuracy in the water depth range from 300 meters to 399 meters, while the support vector machine ISW speed inversion model has high accuracy in the water depth range from 400 meters to 1200 meters and from 83 meters to 299 meters. Therefore, the two kinds of ISW speed inversion models have different advantages, and can be applied to the inversion of the ISW speed in the real ocean.
{"title":"Research on inversion models of internal solitary wave propagation speed in ocean based on least square method and support vector machine","authors":"Keda Liang, Tengfei Liu, Zhe Chang, Meng Zhang, ZhiXin Li, Songsong Huang, Jing Wang","doi":"10.7498/aps.72.20221633","DOIUrl":"https://doi.org/10.7498/aps.72.20221633","url":null,"abstract":"The propagation speed is one of the important parameters of the internal solitary waves(ISWs). How to obtain the ISWs speed through optical remote sensing images accurately and quickly is an important problem to be solved. In this paper, we simulate ISWs optical remote sensing imaging and obtain an experimental database and build the ISWs speed inversion models based on a single-scene optical remote sensing image by using the least squares method and the support vector machine. The accuracy of the ISW speed inversion models were tested by using MODIS Image and GF-4 image data of the South China Sea. The study results show that: The least squares ISW speed inversion model can give the regression equation, which is more intuitive and has less accuracy in the water depth range from 300 meters to 399 meters, while the support vector machine ISW speed inversion model has high accuracy in the water depth range from 400 meters to 1200 meters and from 83 meters to 299 meters. Therefore, the two kinds of ISW speed inversion models have different advantages, and can be applied to the inversion of the ISW speed in the real ocean.","PeriodicalId":6995,"journal":{"name":"Acta Physica Sinica","volume":null,"pages":null},"PeriodicalIF":1.0,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88415916","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Nowadays, there are enormous amounts of energy wasted in the world, most of which is in the form of waste heat. Thermoelectric effect, by converting heat energy into electricity without the release of dangerous substances, has attracted more and more interest from researchers. Since the discovery of graphene, more and more twodimensional layered materials have been reported, which typically own superior electrical, optical and other physical properties than that of bulk materials, and the development of the new theory and experiment technologies stimulates further research for them as well. In this paper, we firstly introduce the measurement methods and techniques that are appropriate for the thermoelectric properties characterizations of two-dimensional materials, and then discuss the current challenging issues related to that. Subsequently, graphene, transition metal disulfides, black phosphorus and other 2D materials in thermoelectric applications are introduced. Finally, we discuss the various strategies to improve the thermoelectric performance and the problems that need to be solved urgently.
{"title":"Recent progresses of two-dimensional layered thermoelectric materials","authors":"Zehao Yu, Lifa Zhang, Jing Wu, Yunshan Zhao","doi":"10.7498/aps.72.20222095","DOIUrl":"https://doi.org/10.7498/aps.72.20222095","url":null,"abstract":"Nowadays, there are enormous amounts of energy wasted in the world, most of which is in the form of waste heat. Thermoelectric effect, by converting heat energy into electricity without the release of dangerous substances, has attracted more and more interest from researchers. Since the discovery of graphene, more and more twodimensional layered materials have been reported, which typically own superior electrical, optical and other physical properties than that of bulk materials, and the development of the new theory and experiment technologies stimulates further research for them as well. In this paper, we firstly introduce the measurement methods and techniques that are appropriate for the thermoelectric properties characterizations of two-dimensional materials, and then discuss the current challenging issues related to that. Subsequently, graphene, transition metal disulfides, black phosphorus and other 2D materials in thermoelectric applications are introduced. Finally, we discuss the various strategies to improve the thermoelectric performance and the problems that need to be solved urgently.","PeriodicalId":6995,"journal":{"name":"Acta Physica Sinica","volume":null,"pages":null},"PeriodicalIF":1.0,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86291947","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Rydberg atom can respond to weak microwave electric field signal in real-time by using its electromagnetically induced transparency effect to realize down conversion of space microwave electric field signal, which can be used as a superheterodyne receiver. The Rydberg atom superheterodyne receiver is a new receiving system composed of Rydberg atoms, photodetectors, and electronic information processing modules. Presently, domestic and foreign scholars have conducted in-depth research on the physical response mechanism of Rydberg atomic superheterodyne receiving technology. However, no complete receiving link analysis model has been established, which is not conducive to optimizing its system performance. Based on the physical mechanism of the Rydberg atom responding to the microwave electric field, this paper introduces the concept of intrinsic expansion coefficient, establishes and experimentally verifies the receiving link model of the Rydberg atom superheterodyne receiver, and briefly discusses the influence of the intrinsic expansion coefficient on the system sensitivity and response characteristics, which provides theoretical guidance for the optimization of the performance of the Rydberg atom superheterodyne receiving system. Last, the Rydberg atomic and the electronic receiving links' sensitivity performance is discussed and compared.
{"title":"Research on Intrinsic Expansion Coefficients in Rydberg Atomic Heterodyne Receiving Link","authors":"Wu Fengchuan, An Qiang, Yao Jiawei, Fu Yunqi","doi":"10.7498/aps.72.20222091","DOIUrl":"https://doi.org/10.7498/aps.72.20222091","url":null,"abstract":"Rydberg atom can respond to weak microwave electric field signal in real-time by using its electromagnetically induced transparency effect to realize down conversion of space microwave electric field signal, which can be used as a superheterodyne receiver. The Rydberg atom superheterodyne receiver is a new receiving system composed of Rydberg atoms, photodetectors, and electronic information processing modules. Presently, domestic and foreign scholars have conducted in-depth research on the physical response mechanism of Rydberg atomic superheterodyne receiving technology. However, no complete receiving link analysis model has been established, which is not conducive to optimizing its system performance. Based on the physical mechanism of the Rydberg atom responding to the microwave electric field, this paper introduces the concept of intrinsic expansion coefficient, establishes and experimentally verifies the receiving link model of the Rydberg atom superheterodyne receiver, and briefly discusses the influence of the intrinsic expansion coefficient on the system sensitivity and response characteristics, which provides theoretical guidance for the optimization of the performance of the Rydberg atom superheterodyne receiving system. Last, the Rydberg atomic and the electronic receiving links' sensitivity performance is discussed and compared.","PeriodicalId":6995,"journal":{"name":"Acta Physica Sinica","volume":null,"pages":null},"PeriodicalIF":1.0,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86403057","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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