Pub Date : 2024-08-01DOI: 10.1088/1674-1056/ad59fc
Chuanxiong Xu, Haoping Yu, Mei Zhou, Xuanting Ji
Measuring the magneto-conductivity induced from impurities may help determine the impurity distribution and reveal the structure of a Weyl semimetal sample. To verify this, we utilize the Gaussian random disorder to simulate charged impurities in a two-node Weyl semimetal model and investigate the impact of charged impurities on magneto-conductivity in Weyl semimetals. We first compute the longitudinal magnetic conductivity and find that it is positive and increases proportionally with the parameter governing the Gaussian distribution of charged impurities, suggesting the presence of negative longitudinal magneto-resistivity. Then we consider both the intra-valley and inter-valley scattering processes to calculate the induced transverse magneto-conductivity in the model. Our findings indicate that both inter-valley and intra-valley scattering processes play important roles in the transverse magneto-conductivity. The locations of Weyl nodes can also be determined by magneto-conductivity measurements. This is possible if the magnetic field strength and the density of charged impurities are known. Alternatively, the measurement of magnetic conductivity may reveal the distribution of charged impurities in a given sample once the locations of the Weyl nodes have been determined. These findings can aid in detecting the structure of a Weyl semimetal sample, enhancing comprehension of magnetotransport in Weyl semimetals and promoting the development of valley electronics.
{"title":"Induced magneto-conductivity in a two-nodeWeyl semimetal under Gaussian random disorder","authors":"Chuanxiong Xu, Haoping Yu, Mei Zhou, Xuanting Ji","doi":"10.1088/1674-1056/ad59fc","DOIUrl":"https://doi.org/10.1088/1674-1056/ad59fc","url":null,"abstract":"Measuring the magneto-conductivity induced from impurities may help determine the impurity distribution and reveal the structure of a Weyl semimetal sample. To verify this, we utilize the Gaussian random disorder to simulate charged impurities in a two-node Weyl semimetal model and investigate the impact of charged impurities on magneto-conductivity in Weyl semimetals. We first compute the longitudinal magnetic conductivity and find that it is positive and increases proportionally with the parameter governing the Gaussian distribution of charged impurities, suggesting the presence of negative longitudinal magneto-resistivity. Then we consider both the intra-valley and inter-valley scattering processes to calculate the induced transverse magneto-conductivity in the model. Our findings indicate that both inter-valley and intra-valley scattering processes play important roles in the transverse magneto-conductivity. The locations of Weyl nodes can also be determined by magneto-conductivity measurements. This is possible if the magnetic field strength and the density of charged impurities are known. Alternatively, the measurement of magnetic conductivity may reveal the distribution of charged impurities in a given sample once the locations of the Weyl nodes have been determined. These findings can aid in detecting the structure of a Weyl semimetal sample, enhancing comprehension of magnetotransport in Weyl semimetals and promoting the development of valley electronics.","PeriodicalId":10253,"journal":{"name":"Chinese Physics B","volume":"20 1","pages":""},"PeriodicalIF":1.7,"publicationDate":"2024-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142209274","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}
Deformation can change the transition pathway of materials under high pressure, thus significantly affects physical and chemical properties of matters. However, accurate pressure calibration under deformation is challenging and thereby causes relatively large pressure uncertainties in deformation experiments, resulting in the synthesis of complex multiphase materials. Here, pressure generations of three types of deformation assemblies were well calibrated in a Walker-type large-volume press (LVP) by electrical resistance measurements combined with finite element simulations (FESs). Hard Al2O3 or diamond pistons in shear and uniaxial deformation assemblies significantly increase the efficiency of pressure generation compared with the conventional quasi-hydrostatic assembly. The uniaxial deformation assembly using flat diamond pistons possesses the highest efficiency in these deformation assemblies. This finding is further confirmed by stress distribution analysis based on FESs. With this deformation assembly, we found shear can effectively promote the transformation of C60 into diamond under high pressure and realized the synthesis of phase-pure diamond at relatively moderate pressure and temperature conditions. The present developed techniques will help improve pressure efficiencies in LVP and explore the new physical and chemical properties of materials under deformation in both science and technology.
{"title":"Pressure generation under deformation in a large-volume press","authors":"Saisai Wang, Xinyu Zhao, Kuo Hu, Bingtao Feng, Xuyuan Hou, Yiming Zhang, Shucheng Liu, Yuchen Shang, Zhaodong Liu, Mingguang Yao, Bingbing Liu","doi":"10.1088/1674-1056/ad58c6","DOIUrl":"https://doi.org/10.1088/1674-1056/ad58c6","url":null,"abstract":"Deformation can change the transition pathway of materials under high pressure, thus significantly affects physical and chemical properties of matters. However, accurate pressure calibration under deformation is challenging and thereby causes relatively large pressure uncertainties in deformation experiments, resulting in the synthesis of complex multiphase materials. Here, pressure generations of three types of deformation assemblies were well calibrated in a Walker-type large-volume press (LVP) by electrical resistance measurements combined with finite element simulations (FESs). Hard Al<sub>2</sub>O<sub>3</sub> or diamond pistons in shear and uniaxial deformation assemblies significantly increase the efficiency of pressure generation compared with the conventional quasi-hydrostatic assembly. The uniaxial deformation assembly using flat diamond pistons possesses the highest efficiency in these deformation assemblies. This finding is further confirmed by stress distribution analysis based on FESs. With this deformation assembly, we found shear can effectively promote the transformation of C<sub>60</sub> into diamond under high pressure and realized the synthesis of phase-pure diamond at relatively moderate pressure and temperature conditions. The present developed techniques will help improve pressure efficiencies in LVP and explore the new physical and chemical properties of materials under deformation in both science and technology.","PeriodicalId":10253,"journal":{"name":"Chinese Physics B","volume":"139 1","pages":""},"PeriodicalIF":1.7,"publicationDate":"2024-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142209273","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}
Pub Date : 2024-08-01DOI: 10.1088/1674-1056/ad5c3d
Ao Xu, Pingping Gan, Xiang Wan, Yuanjie Shi
The spatial distributions of different kinds of ions are usually not completely the same in the process of extracting. In order to study the reason for the different characteristics of ion extraction, a simplified simulation model of Cu+ and Cr+ ions extraction process was established by 2D3V (two-dimensional in space and three-dimensional in velocity space) particle-in-cell (PIC) method. The effects of different extraction voltages from 0 V to 500 V on the density distribution of Cu+ and Cr+ ions and the change of plasma emission surface were analyzed. On the basis of this model, the ion density distribution characteristics of Cu+ ions mixed with Li+, Mg+, K+, Fe+, Y+, Ag+, Xe+, Au+, and Pb+ ions respectively under 200-V extraction voltage are further simulated, and it is revealed that the atomic mass of the ions is the key reason for different ion density distributions when different kinds of ions are mixed and extracted, which provides support for further understanding of ion extraction characteristics.
在萃取过程中，不同种类离子的空间分布通常不完全相同。为了研究离子萃取特性不同的原因，采用 2D3V（空间二维、速度空间三维）粒子入胞法（PIC）建立了 Cu+ 和 Cr+ 离子萃取过程的简化模拟模型。分析了从 0 V 到 500 V 的不同萃取电压对 Cu+ 和 Cr+ 离子密度分布和等离子体发射面变化的影响。在此基础上，进一步模拟了在 200 V 萃取电压下，Cu+ 离子分别与 Li+、Mg+、K+、Fe+、Y+、Ag+、Xe+、Au+ 和 Pb+ 离子混合后的离子密度分布特征，发现离子的原子质量是不同种类离子混合萃取时离子密度分布不同的关键原因，为进一步理解离子萃取特征提供了支持。
{"title":"Influence of ion species on extraction characteristics of mixed ion beams","authors":"Ao Xu, Pingping Gan, Xiang Wan, Yuanjie Shi","doi":"10.1088/1674-1056/ad5c3d","DOIUrl":"https://doi.org/10.1088/1674-1056/ad5c3d","url":null,"abstract":"The spatial distributions of different kinds of ions are usually not completely the same in the process of extracting. In order to study the reason for the different characteristics of ion extraction, a simplified simulation model of Cu<sup>+</sup> and Cr<sup>+</sup> ions extraction process was established by 2D3V (two-dimensional in space and three-dimensional in velocity space) particle-in-cell (PIC) method. The effects of different extraction voltages from 0 V to 500 V on the density distribution of Cu<sup>+</sup> and Cr<sup>+</sup> ions and the change of plasma emission surface were analyzed. On the basis of this model, the ion density distribution characteristics of Cu<sup>+</sup> ions mixed with Li<sup>+</sup>, Mg<sup>+</sup>, K<sup>+</sup>, Fe<sup>+</sup>, Y<sup>+</sup>, Ag<sup>+</sup>, Xe<sup>+</sup>, Au<sup>+</sup>, and Pb<sup>+</sup> ions respectively under 200-V extraction voltage are further simulated, and it is revealed that the atomic mass of the ions is the key reason for different ion density distributions when different kinds of ions are mixed and extracted, which provides support for further understanding of ion extraction characteristics.","PeriodicalId":10253,"journal":{"name":"Chinese Physics B","volume":"32 1","pages":""},"PeriodicalIF":1.7,"publicationDate":"2024-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142209270","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}
Pub Date : 2024-08-01DOI: 10.1088/1674-1056/ad5c3b
Ming-Hao Wang, Hua Lü
Leveraging the extraordinary phenomena of quantum superposition and quantum correlation, quantum computing offers unprecedented potential for addressing challenges beyond the reach of classical computers. This paper tackles two pivotal challenges in the realm of quantum computing: firstly, the development of an effective encoding protocol for translating classical data into quantum states, a critical step for any quantum computation. Different encoding strategies can significantly influence quantum computer performance. Secondly, we address the need to counteract the inevitable noise that can hinder quantum acceleration. Our primary contribution is the introduction of a novel variational data encoding method, grounded in quantum regression algorithm models. By adapting the learning concept from machine learning, we render data encoding a learnable process. This allowed us to study the role of quantum correlation in data encoding. Through numerical simulations of various regression tasks, we demonstrate the efficacy of our variational data encoding, particularly post-learning from instructional data. Moreover, we delve into the role of quantum correlation in enhancing task performance, especially in noisy environments. Our findings underscore the critical role of quantum correlation in not only bolstering performance but also in mitigating noise interference, thus advancing the frontier of quantum computing.
{"title":"Variational data encoding and correlations in quantum-enhanced machine learning","authors":"Ming-Hao Wang, Hua Lü","doi":"10.1088/1674-1056/ad5c3b","DOIUrl":"https://doi.org/10.1088/1674-1056/ad5c3b","url":null,"abstract":"Leveraging the extraordinary phenomena of quantum superposition and quantum correlation, quantum computing offers unprecedented potential for addressing challenges beyond the reach of classical computers. This paper tackles two pivotal challenges in the realm of quantum computing: firstly, the development of an effective encoding protocol for translating classical data into quantum states, a critical step for any quantum computation. Different encoding strategies can significantly influence quantum computer performance. Secondly, we address the need to counteract the inevitable noise that can hinder quantum acceleration. Our primary contribution is the introduction of a novel variational data encoding method, grounded in quantum regression algorithm models. By adapting the learning concept from machine learning, we render data encoding a learnable process. This allowed us to study the role of quantum correlation in data encoding. Through numerical simulations of various regression tasks, we demonstrate the efficacy of our variational data encoding, particularly post-learning from instructional data. Moreover, we delve into the role of quantum correlation in enhancing task performance, especially in noisy environments. Our findings underscore the critical role of quantum correlation in not only bolstering performance but also in mitigating noise interference, thus advancing the frontier of quantum computing.","PeriodicalId":10253,"journal":{"name":"Chinese Physics B","volume":"7 1","pages":""},"PeriodicalIF":1.7,"publicationDate":"2024-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142209272","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}
Pub Date : 2024-08-01DOI: 10.1088/1674-1056/ad5274
Zhi-Hao Yang, Yan-Long Yang
In public goods games, punishments and rewards have been shown to be effective mechanisms for maintaining individual cooperation. However, punishments and rewards are costly to incentivize cooperation. Therefore, the generation of costly penalties and rewards has been a complex problem in promoting the development of cooperation. In real society, specialized institutions exist to punish evil people or reward good people by collecting taxes. We propose a strong altruistic punishment or reward strategy in the public goods game through this phenomenon. Through theoretical analysis and numerical calculation, we can get that tax-based strong altruistic punishment (reward) has more evolutionary advantages than traditional strong altruistic punishment (reward) in maintaining cooperation and tax-based strong altruistic reward leads to a higher level of cooperation than tax-based strong altruistic punishment.
{"title":"Evolutionary dynamics of tax-based strong altruistic reward and punishment in a public goods game","authors":"Zhi-Hao Yang, Yan-Long Yang","doi":"10.1088/1674-1056/ad5274","DOIUrl":"https://doi.org/10.1088/1674-1056/ad5274","url":null,"abstract":"In public goods games, punishments and rewards have been shown to be effective mechanisms for maintaining individual cooperation. However, punishments and rewards are costly to incentivize cooperation. Therefore, the generation of costly penalties and rewards has been a complex problem in promoting the development of cooperation. In real society, specialized institutions exist to punish evil people or reward good people by collecting taxes. We propose a strong altruistic punishment or reward strategy in the public goods game through this phenomenon. Through theoretical analysis and numerical calculation, we can get that tax-based strong altruistic punishment (reward) has more evolutionary advantages than traditional strong altruistic punishment (reward) in maintaining cooperation and tax-based strong altruistic reward leads to a higher level of cooperation than tax-based strong altruistic punishment.","PeriodicalId":10253,"journal":{"name":"Chinese Physics B","volume":"42 1","pages":""},"PeriodicalIF":1.7,"publicationDate":"2024-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142209276","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}
Ultraviolet photodetectors (UV PDs) are widely used in civilian, scientific, and military fields due to their high sensitivity and low false alarm rates. We present a temperature-dependent Lewis acid p-type doping method for transition metal dichalcogenides (TMDs), which can effectively be used to extend the optical response range. The p-type doping based on surface charge transfer involves the chemical adsorption of the Lewis acid SnCl4 as a light absorption layer on the surface of WS2, significantly enhancing its UV photodetection performance. Under 365 nm laser irradiation, WS2 PDs exhibit response speed of 24 ms/20 ms, responsivity of 660 mA/W, detectivity of 3.3 × 1011 Jones, and external quantum efficiency of 226%. Moreover, we successfully apply this doping method to other TMDs materials (such as MoS2, MoSe2, and WSe2) and fabricate WS2 lateral p–n heterojunction PDs.
{"title":"Lewis acid-doped transition metal dichalcogenides for ultraviolet–visible photodetectors","authors":"Heng Yang, Mingjun Ma, Yongfeng Pei, Yufan Kang, Jialu Yan, Dong He, Changzhong Jiang, Wenqing Li, Xiangheng Xiao","doi":"10.1088/1674-1056/ad597f","DOIUrl":"https://doi.org/10.1088/1674-1056/ad597f","url":null,"abstract":"Ultraviolet photodetectors (UV PDs) are widely used in civilian, scientific, and military fields due to their high sensitivity and low false alarm rates. We present a temperature-dependent Lewis acid p-type doping method for transition metal dichalcogenides (TMDs), which can effectively be used to extend the optical response range. The p-type doping based on surface charge transfer involves the chemical adsorption of the Lewis acid SnCl<sub>4</sub> as a light absorption layer on the surface of WS<sub>2</sub>, significantly enhancing its UV photodetection performance. Under 365 nm laser irradiation, WS<sub>2</sub> PDs exhibit response speed of 24 ms/20 ms, responsivity of 660 mA/W, detectivity of 3.3 × 10<sup>11</sup> Jones, and external quantum efficiency of 226%. Moreover, we successfully apply this doping method to other TMDs materials (such as MoS<sub>2</sub>, MoSe<sub>2</sub>, and WSe<sub>2</sub>) and fabricate WS<sub>2</sub> lateral p–n heterojunction PDs.","PeriodicalId":10253,"journal":{"name":"Chinese Physics B","volume":"22 1","pages":""},"PeriodicalIF":1.7,"publicationDate":"2024-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142209295","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}
Pub Date : 2024-08-01DOI: 10.1088/1674-1056/ad58c5
Ying Jing, Youguo Wang, Qiqing Zhai, Xianli Sun
Social networks are inevitably subject to disruptions from the physical world, such as sudden internet outages that sever local connections and impede information flow. While Gaussian white noise, commonly used to simulate stochastic disruptions, only fluctuates within a narrow range around its mean and fails to capture large-scale variations, Lévy noise can effectively compensate for this limitation. Therefore, a susceptible–infected–removed rumor propagation model with Lévy noise is constructed on homogeneous and heterogeneous networks, respectively. Then, the existence of a global positive solution and the asymptotic path-wise of the solution are derived on heterogeneous networks, and the sufficient conditions of rumor extinction and persistence are investigated. Subsequently, theoretical results are verified through numerical calculations and the sensitivity analysis related to the threshold is conducted on the model parameters. Through simulation experiments on Watts–Strogatz (WS) and Barabási–Albert networks, it is found that the addition of noise can inhibit the spread of rumors, resulting in a stochastic resonance phenomenon, and the optimal noise intensity is obtained on the WS network. The validity of the model is verified on three real datasets by particle swarm optimization algorithm.
{"title":"Dynamic properties of rumor propagation model induced by Lévy noise on social networks","authors":"Ying Jing, Youguo Wang, Qiqing Zhai, Xianli Sun","doi":"10.1088/1674-1056/ad58c5","DOIUrl":"https://doi.org/10.1088/1674-1056/ad58c5","url":null,"abstract":"Social networks are inevitably subject to disruptions from the physical world, such as sudden internet outages that sever local connections and impede information flow. While Gaussian white noise, commonly used to simulate stochastic disruptions, only fluctuates within a narrow range around its mean and fails to capture large-scale variations, Lévy noise can effectively compensate for this limitation. Therefore, a susceptible–infected–removed rumor propagation model with Lévy noise is constructed on homogeneous and heterogeneous networks, respectively. Then, the existence of a global positive solution and the asymptotic path-wise of the solution are derived on heterogeneous networks, and the sufficient conditions of rumor extinction and persistence are investigated. Subsequently, theoretical results are verified through numerical calculations and the sensitivity analysis related to the threshold is conducted on the model parameters. Through simulation experiments on Watts–Strogatz (WS) and Barabási–Albert networks, it is found that the addition of noise can inhibit the spread of rumors, resulting in a stochastic resonance phenomenon, and the optimal noise intensity is obtained on the WS network. The validity of the model is verified on three real datasets by particle swarm optimization algorithm.","PeriodicalId":10253,"journal":{"name":"Chinese Physics B","volume":"47 1","pages":""},"PeriodicalIF":1.7,"publicationDate":"2024-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142209296","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}
Pub Date : 2024-08-01DOI: 10.1088/1674-1056/ad5980
Linhua Jia, Xinghua Qu, Fumin Zhang
Laser absorption spectroscopy has proven to be an effective approach for gas sensing, which plays an important role in the fields of military, industry, medicine and basic research. This paper presents a multiplexed gas sensing system based on optical frequency comb (OFC) calibrated frequency-modulated continuous-wave (FMCW) tuning nonlinearity. The system can be used for multi-parameter synchronous measurement of gas absorption spectrum and multiplexed optical path. Multi-channel parallel detection is realized by combining wavelength division multiplexing (WDM) and frequency division multiplexing (FDM) techniques. By introducing nonlinear optical crystals, broadband spectrum detection is simultaneously achieved over a bandwidth of hundreds of nanometers. An OFC with ultra-high frequency stability is used as the frequency calibration source, which guarantees the measurement accuracy. The test samples involve H13C14N, C2H2 and Rb vapor cells of varying densities and 5 parallel measurement experiments are designed. The results show that the measurement accuracies of spectral absorption line and the optical path are 150 MHz and 20 μm, respectively. The scheme offers the advantages of multiplexed, multi-parameter, wide spectrum and high resolution detection, which can realize the identification of multi-gas components and the high-precision inversion of absorption lines under different environments. The proposed sensor demonstrates great potential in the field of high-resolution absorption spectrum measurement for gas sensing applications.
{"title":"Frequency-modulated continuous-wave multiplexed gas sensing based on optical frequency comb calibration","authors":"Linhua Jia, Xinghua Qu, Fumin Zhang","doi":"10.1088/1674-1056/ad5980","DOIUrl":"https://doi.org/10.1088/1674-1056/ad5980","url":null,"abstract":"Laser absorption spectroscopy has proven to be an effective approach for gas sensing, which plays an important role in the fields of military, industry, medicine and basic research. This paper presents a multiplexed gas sensing system based on optical frequency comb (OFC) calibrated frequency-modulated continuous-wave (FMCW) tuning nonlinearity. The system can be used for multi-parameter synchronous measurement of gas absorption spectrum and multiplexed optical path. Multi-channel parallel detection is realized by combining wavelength division multiplexing (WDM) and frequency division multiplexing (FDM) techniques. By introducing nonlinear optical crystals, broadband spectrum detection is simultaneously achieved over a bandwidth of hundreds of nanometers. An OFC with ultra-high frequency stability is used as the frequency calibration source, which guarantees the measurement accuracy. The test samples involve H<sup>13</sup>C<sup>14</sup>N, C<sub>2</sub>H<sub>2</sub> and Rb vapor cells of varying densities and 5 parallel measurement experiments are designed. The results show that the measurement accuracies of spectral absorption line and the optical path are 150 MHz and 20 μm, respectively. The scheme offers the advantages of multiplexed, multi-parameter, wide spectrum and high resolution detection, which can realize the identification of multi-gas components and the high-precision inversion of absorption lines under different environments. The proposed sensor demonstrates great potential in the field of high-resolution absorption spectrum measurement for gas sensing applications.","PeriodicalId":10253,"journal":{"name":"Chinese Physics B","volume":"9 1","pages":""},"PeriodicalIF":1.7,"publicationDate":"2024-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142209277","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}
Pub Date : 2024-08-01DOI: 10.1088/1674-1056/ad6a0e
Yaoyuan Wang, Long You, Kai Chang, Hongxin Yang
Topological magnetism with strong robustness, nanoscale dimensions and ultralow driving current density (∼ 106 A/m2) is promising for applications in information sensing, storage, and processing, and thus sparking widespread research interest. Exploring candidate material systems with nanoscale size and easily tunable properties is a key for realizing practical topological magnetism-based spintronic devices. Here, we propose a class of ultrathin heterostructures, Fe/Bi2O2X (X = S, Se, Te) by deposing metal Fe on quasi-two-dimensional (2D) bismuth oxychalcogenides Bi2O2X (X = S, Se, Te) with excellent ferroelectric/ferroelastic properties. Large Dzyaloshinskii–Moriya interaction (DMI) and topological magnetism can be realized. Our atomistic spin dynamics simulations demonstrate that field-free vortex–antivortex loops and sub-10 nm skyrmions exist in Fe/Bi2O2S and Fe/Bi2O2Se interfaces, respectively. These results provide a possible strategy to tailor topological magnetism in ultrathin magnets/2D materials interfaces, which is extremely vital for spintronics applications.
{"title":"Dzyaloshinskii–Moriya interaction and field-free sub-10 nm topological magnetism in Fe/bismuth oxychalcogenides heterostructures","authors":"Yaoyuan Wang, Long You, Kai Chang, Hongxin Yang","doi":"10.1088/1674-1056/ad6a0e","DOIUrl":"https://doi.org/10.1088/1674-1056/ad6a0e","url":null,"abstract":"Topological magnetism with strong robustness, nanoscale dimensions and ultralow driving current density (∼ 10<sup>6</sup> A/m<sup>2</sup>) is promising for applications in information sensing, storage, and processing, and thus sparking widespread research interest. Exploring candidate material systems with nanoscale size and easily tunable properties is a key for realizing practical topological magnetism-based spintronic devices. Here, we propose a class of ultrathin heterostructures, Fe/Bi<sub>2</sub>O<sub>2</sub><italic toggle=\"yes\">X</italic> (<italic toggle=\"yes\">X</italic> = S, Se, Te) by deposing metal Fe on quasi-two-dimensional (2D) bismuth oxychalcogenides Bi<sub>2</sub>O<sub>2</sub><italic toggle=\"yes\">X</italic> (<italic toggle=\"yes\">X</italic> = S, Se, Te) with excellent ferroelectric/ferroelastic properties. Large Dzyaloshinskii–Moriya interaction (DMI) and topological magnetism can be realized. Our atomistic spin dynamics simulations demonstrate that field-free vortex–antivortex loops and sub-10 nm skyrmions exist in Fe/Bi<sub>2</sub>O<sub>2</sub>S and Fe/Bi<sub>2</sub>O<sub>2</sub>Se interfaces, respectively. These results provide a possible strategy to tailor topological magnetism in ultrathin magnets/2D materials interfaces, which is extremely vital for spintronics applications.","PeriodicalId":10253,"journal":{"name":"Chinese Physics B","volume":"55 1","pages":""},"PeriodicalIF":1.7,"publicationDate":"2024-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142209269","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}
Pub Date : 2024-08-01DOI: 10.1088/1674-1056/ad5aed
Yongnan Jia, Jiali Han, Qing Li
This paper presents a comprehensive framework for analyzing phase transitions in collective models such as the Vicsek model under various noise types. The Vicsek model, focusing on understanding the collective behaviors of social animals, is known due to its discontinuous phase transitions under vector noise. However, its behavior under scalar noise remains less conclusive. Renowned for its efficacy in the analysis of complex systems under both equilibrium and non-equilibrium states, the eigen microstate method is employed here for a quantitative examination of the phase transitions in the Vicsek model under both vector and scalar noises. The study finds that the Vicsek model exhibits discontinuous phase transitions regardless of noise type. Furthermore, the dichotomy method is utilized to identify the critical points for these phase transitions. A significant finding is the observed increase in the critical point for discontinuous phase transitions with escalation of population density.
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