Pub Date : 2024-10-26DOI: 10.1016/j.physe.2024.116127
Subhajit Pal, Colin Benjamin
We predict that the appearance of zero-energy Yu-Shiba-Rusinov(YSR) bound states in two different setups, metal-spin flipper-metal-s-wave superconductor () and superconductor-metal-spin flipper-metal-superconductor () junctions, can cause a multi-fold enhancement of surface odd-frequency superconducting pairing. On the other hand, in the absence of these bound states, even-frequency pairing dominates surface odd-frequency pairing. Specifically, in the Josephson junction, the emergence of zero energy YSR bound states leads to a junction transition and surface odd-frequency pairing dominance. Notably, odd-frequency pairing vanishes in the absence of the YSR-bound states. Interestingly, the equal spin–triplet pairing is the dominant component in odd-frequency superconductivity in both setups, which could have important implications for superconducting spintronics. Overall, our findings may help to detect the presence of YSR-bound states through the observation of surface odd-frequency pairing and contribute to a better understanding of their relationship.
{"title":"Yu-Shiba-Rusinov bound states boost surface odd-frequency pairing","authors":"Subhajit Pal, Colin Benjamin","doi":"10.1016/j.physe.2024.116127","DOIUrl":"10.1016/j.physe.2024.116127","url":null,"abstract":"<div><div>We predict that the appearance of zero-energy Yu-Shiba-Rusinov(YSR) bound states in two different setups, metal-spin flipper-metal-s-wave superconductor (<span><math><mrow><msub><mrow><mi>N</mi></mrow><mrow><mn>1</mn></mrow></msub><mo>−</mo><mi>s</mi><mi>f</mi><mo>−</mo><msub><mrow><mi>N</mi></mrow><mrow><mn>2</mn></mrow></msub><mo>−</mo><mi>S</mi></mrow></math></span>) and superconductor-metal-spin flipper-metal-superconductor (<span><math><mrow><mi>S</mi><mo>−</mo><msub><mrow><mi>N</mi></mrow><mrow><mn>1</mn></mrow></msub><mo>−</mo><mi>s</mi><mi>f</mi><mo>−</mo><msub><mrow><mi>N</mi></mrow><mrow><mn>2</mn></mrow></msub><mo>−</mo><mi>S</mi></mrow></math></span>) junctions, can cause a multi-fold enhancement of surface odd-frequency superconducting pairing. On the other hand, in the absence of these bound states, even-frequency pairing dominates surface odd-frequency pairing. Specifically, in the <span><math><mrow><mi>S</mi><mo>−</mo><msub><mrow><mi>N</mi></mrow><mrow><mn>1</mn></mrow></msub><mo>−</mo><mi>s</mi><mi>f</mi><mo>−</mo><msub><mrow><mi>N</mi></mrow><mrow><mn>2</mn></mrow></msub><mo>−</mo><mi>S</mi></mrow></math></span> Josephson junction, the emergence of zero energy YSR bound states leads to a <span><math><mrow><mn>0</mn><mo>−</mo><mi>π</mi></mrow></math></span> junction transition and surface odd-frequency pairing dominance. Notably, odd-frequency pairing vanishes in the absence of the YSR-bound states. Interestingly, the equal spin–triplet pairing is the dominant component in odd-frequency superconductivity in both setups, which could have important implications for superconducting spintronics. Overall, our findings may help to detect the presence of YSR-bound states through the observation of surface odd-frequency pairing and contribute to a better understanding of their relationship.</div></div>","PeriodicalId":20181,"journal":{"name":"Physica E-low-dimensional Systems & Nanostructures","volume":"166 ","pages":"Article 116127"},"PeriodicalIF":2.9,"publicationDate":"2024-10-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142534020","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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 : 2024-10-16DOI: 10.1016/j.physe.2024.116130
Taiyu Hao , Qingyi Feng , Biyi Wang , Zhiwei Li , Bo Li , Hongxiang Deng
In the domain of photocatalysis, type I heterojunctions have received limited attention, and the quest for effective type I photocatalysts persists. This study introduces a novel type I heterostructure, ZnS/Ga2SSe, and gives a systematic investigation of its electronic properties, optical properties, and photocatalytic performance by DFT calculations. Electronic properties show that ZnS/Ga2SSe system has a type I band alignment with a 2.26 eV band gap. Different from traditional type I heterostructure, ZnS/Ga2SSe has an obvious interfacial electric field and a potential barrier, which promotes spatial charge separation and addresses the drawback of easy recombination of photo-generated carriers in traditional type I heterojunctions. The calculated results of Gibbs free energy show that under the 3.3 eV external potential and pH = 14, water splitting reaction can be achieved spontaneously. Moreover, the heterojunction shows good optical absorption in visible regions and 22.28 % STH efficiency which is higher than the reported type I photocatalysts. The biaxial strain can modulate the electronic structure and maintain type I alignment. Tensile can reduce the bandgap and enhance optical absorption, while compression is the opposite. Under 4 % tensile, STH efficiency can reach 40.3 %, while −4 % compression it will decrease to 10.3 %. These conclusions underline the potential of the ZnS/Ga2SSe heterojunction as a promising photocatalytic material candidate for water splitting and type I heterojunctions is worth exploring as photocatalysis.
在光催化领域，I型异质结受到的关注有限，人们一直在寻求有效的I型光催化剂。本研究介绍了一种新型 I 型异质结构 ZnS/Ga2SSe，并通过 DFT 计算对其电子特性、光学特性和光催化性能进行了系统研究。电子特性表明，ZnS/Ga2SSe 系统具有 2.26 eV 带隙的 I 型带排列。与传统的 I 型异质结构不同，ZnS/Ga2SSe 具有明显的界面电场和势垒，能促进空间电荷分离，解决了传统 I 型异质结中光生载流子易重组的缺点。吉布斯自由能的计算结果表明，在 3.3 eV 的外部电势和 pH = 14 的条件下，可以自发地实现水分裂反应。此外，该异质结在可见光区域具有良好的光吸收性能，STH 效率为 22.28%，高于已报道的 I 型光催化剂。双轴应变可以调节电子结构并保持 I 型排列。拉伸能减小带隙并增强光吸收，而压缩则相反。拉伸 4% 时，STH 效率可达 40.3%，而压缩 -4% 时则降至 10.3%。这些结论强调了 ZnS/Ga2SSe 异质结作为一种有前途的光催化材料用于水分离的潜力，而 I 型异质结作为光催化材料也值得探索。
{"title":"Overall water splitting of type-I vdW heterojunction ZnS/Ga2SSe","authors":"Taiyu Hao , Qingyi Feng , Biyi Wang , Zhiwei Li , Bo Li , Hongxiang Deng","doi":"10.1016/j.physe.2024.116130","DOIUrl":"10.1016/j.physe.2024.116130","url":null,"abstract":"<div><div>In the domain of photocatalysis, type I heterojunctions have received limited attention, and the quest for effective type I photocatalysts persists. This study introduces a novel type I heterostructure, ZnS/Ga<sub>2</sub>SSe, and gives a systematic investigation of its electronic properties, optical properties, and photocatalytic performance by DFT calculations. Electronic properties show that ZnS/Ga<sub>2</sub>SSe system has a type I band alignment with a 2.26 eV band gap. Different from traditional type I heterostructure, ZnS/Ga<sub>2</sub>SSe has an obvious interfacial electric field and a potential barrier, which promotes spatial charge separation and addresses the drawback of easy recombination of photo-generated carriers in traditional type I heterojunctions. The calculated results of Gibbs free energy show that under the 3.3 eV external potential and pH = 14, water splitting reaction can be achieved spontaneously. Moreover, the heterojunction shows good optical absorption in visible regions and 22.28 % STH efficiency which is higher than the reported type I photocatalysts. The biaxial strain can modulate the electronic structure and maintain type I alignment. Tensile can reduce the bandgap and enhance optical absorption, while compression is the opposite. Under 4 % tensile, STH efficiency can reach 40.3 %, while −4 % compression it will decrease to 10.3 %. These conclusions underline the potential of the ZnS/Ga<sub>2</sub>SSe heterojunction as a promising photocatalytic material candidate for water splitting and type I heterojunctions is worth exploring as photocatalysis.</div></div>","PeriodicalId":20181,"journal":{"name":"Physica E-low-dimensional Systems & Nanostructures","volume":"165 ","pages":"Article 116130"},"PeriodicalIF":2.9,"publicationDate":"2024-10-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142534819","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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 : 2024-10-12DOI: 10.1016/j.physe.2024.116131
Yin Ren , Lin He , Yunfei He , Yahong Wang , Sisi Li , Luming Zhou , Peng Ye , Rongli Gao , Gang Chen , Wei Cai , Chunlin Fu
Combining perovskite with infrared quantum dots to construct a core-shell nanostructure nanowire array solar cell can increase the light absorption range and enhance the light absorption and carrier transport efficiency of the solar cell. However, the preparation of a perovskite absorber layer on a nanowire array with quantum dots often presents issues such as high roughness and a large number of lattice defects, which have a negative impact on the photovoltaic performance. The anti-solvent method is a commonly used technique to improve the quality of perovskite. The temperature variation of the anti-solvent can change solubility, and influence the reaction rate and crystal formation process of perovskite, thus affecting its photovoltaic performance. In this study, the quality of perovskite in the core-shell nanostructure nanowire array was improved by controlling the temperature of the anti-solvent (toluene). Experimental results show that as the temperature of toluene increases, the photovoltaic performance is gradually improved. When the toluene temperature was maintained at 75 °C, the device exhibited significantly improved photovoltaic performance with an efficiency of 12.64 %, surpassing the efficiency obtained without any anti-solvent modification. As the temperature of the anti-solvent increases, the absorption of visible and near-infrared light spectrum by the nanowire arrays is enhanced, which promotes the efficient generation of photo-generated carriers. Furthermore, defects in the nanowire arrays gradually decrease, leading to a reduction in carrier recombination. These findings provide valuable insights for advancing core-shell nanostructure nanowire array solar cells.
{"title":"The key role of anti-solvent temperature in quantum dot/perovskite core-shell nanowire array solar cells","authors":"Yin Ren , Lin He , Yunfei He , Yahong Wang , Sisi Li , Luming Zhou , Peng Ye , Rongli Gao , Gang Chen , Wei Cai , Chunlin Fu","doi":"10.1016/j.physe.2024.116131","DOIUrl":"10.1016/j.physe.2024.116131","url":null,"abstract":"<div><div>Combining perovskite with infrared quantum dots to construct a core-shell nanostructure nanowire array solar cell can increase the light absorption range and enhance the light absorption and carrier transport efficiency of the solar cell. However, the preparation of a perovskite absorber layer on a nanowire array with quantum dots often presents issues such as high roughness and a large number of lattice defects, which have a negative impact on the photovoltaic performance. The anti-solvent method is a commonly used technique to improve the quality of perovskite. The temperature variation of the anti-solvent can change solubility, and influence the reaction rate and crystal formation process of perovskite, thus affecting its photovoltaic performance. In this study, the quality of perovskite in the core-shell nanostructure nanowire array was improved by controlling the temperature of the anti-solvent (toluene). Experimental results show that as the temperature of toluene increases, the photovoltaic performance is gradually improved. When the toluene temperature was maintained at 75 °C, the device exhibited significantly improved photovoltaic performance with an efficiency of 12.64 %, surpassing the efficiency obtained without any anti-solvent modification. As the temperature of the anti-solvent increases, the absorption of visible and near-infrared light spectrum by the nanowire arrays is enhanced, which promotes the efficient generation of photo-generated carriers. Furthermore, defects in the nanowire arrays gradually decrease, leading to a reduction in carrier recombination. These findings provide valuable insights for advancing core-shell nanostructure nanowire array solar cells.</div></div>","PeriodicalId":20181,"journal":{"name":"Physica E-low-dimensional Systems & Nanostructures","volume":"165 ","pages":"Article 116131"},"PeriodicalIF":2.9,"publicationDate":"2024-10-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142446081","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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 : 2024-10-11DOI: 10.1016/j.physe.2024.116121
Jhalak Gupta , Arham S. Ahmed , Pushpendra , Ameer Azam
In this research work, we prepared NiO@SnO2 (N1), NiO@ZnO (N2) and NiO@MnO2 (N3) core-shell nanocomposites using sol-gel route. Prepared samples were investigated for their different properties employing various characterization techniques. The morphology and structure of the nanocomposites were characterized by transmission electron microscopy, X-ray photoelectron spectroscopy, Fourier transform Infrared Spectroscopy, X-ray diffraction analysis. Furthermore, the optical properties were analyzed using UV–Vis Spectroscopy, Photoluminescence Spectroscopy. In addition, the supercapacitive performances were examined by cyclic voltammogram (CV), galvanostatic charge-discharge(GCD) and electrochemical impedance spectroscopy (EIS). The electrochemical results indicate that all the prepared composites exhibits good electrochemical performance but N2 depicts superior results among all. The specific capacitance obtained for N2 is 720 F/g at 1 A g−1 and excellent cycling stability (96.5 % retention after 6000 cycles at 1 A g−1). Therefore, this wok offers meaningful reference for supercapacitor applications in the future.
在这项研究工作中，我们采用溶胶-凝胶法制备了 NiO@SnO2（N1）、NiO@ZnO（N2）和 NiO@MnO2（N3）核壳纳米复合材料。利用各种表征技术对制备的样品进行了不同性质的研究。透射电子显微镜、X 射线光电子能谱、傅立叶变换红外光谱和 X 射线衍射分析对纳米复合材料的形貌和结构进行了表征。此外，还利用紫外可见光谱和光致发光光谱分析了纳米复合材料的光学特性。此外，还通过循环伏安图（CV）、电静态充放电（GCD）和电化学阻抗谱（EIS）对超级电容器性能进行了检测。电化学结果表明，所有制备的复合材料都表现出良好的电化学性能，但其中 N2 的电化学性能更优。在 1 A g-1 的条件下，N2 的比电容为 720 F/g，循环稳定性极佳（在 1 A g-1 条件下循环 6000 次后，电容保持率为 96.5%）。因此，这种炒锅为超级电容器的未来应用提供了有意义的参考。
{"title":"Comparative study of NiO based core-shell nanocomposites to high performance supercapacitor electrode materials","authors":"Jhalak Gupta , Arham S. Ahmed , Pushpendra , Ameer Azam","doi":"10.1016/j.physe.2024.116121","DOIUrl":"10.1016/j.physe.2024.116121","url":null,"abstract":"<div><div>In this research work, we prepared NiO@SnO<sub>2</sub> (N1), NiO@ZnO (N2) and NiO@MnO<sub>2</sub> (N3) core-shell nanocomposites using sol-gel route. Prepared samples were investigated for their different properties employing various characterization techniques. The morphology and structure of the nanocomposites were characterized by transmission electron microscopy, X-ray photoelectron spectroscopy, Fourier transform Infrared Spectroscopy, X-ray diffraction analysis. Furthermore, the optical properties were analyzed using UV–Vis Spectroscopy, Photoluminescence Spectroscopy. In addition, the supercapacitive performances were examined by cyclic voltammogram (CV), galvanostatic charge-discharge(GCD) and electrochemical impedance spectroscopy (EIS). The electrochemical results indicate that all the prepared composites exhibits good electrochemical performance but N2 depicts superior results among all. The specific capacitance obtained for N2 is 720 F/g at 1 A g<sup>−1</sup> and excellent cycling stability (96.5 % retention after 6000 cycles at 1 A g<sup>−1</sup>). Therefore, this wok offers meaningful reference for supercapacitor applications in the future.</div></div>","PeriodicalId":20181,"journal":{"name":"Physica E-low-dimensional Systems & Nanostructures","volume":"165 ","pages":"Article 116121"},"PeriodicalIF":2.9,"publicationDate":"2024-10-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142534821","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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 : 2024-10-10DOI: 10.1016/j.physe.2024.116125
Nooshin Rashidi , Rostam Moradian
This work theoretically investigates the thermoelectric properties of boron phosphide nanotubes (BPNTs) using the tight-binding model, Green function method, and Kubo formalism, focusing on a zigzag BPNT with indices (20, 0). The tight binding parameters obtained by matching its band structure with calculated density functional theory band structure. The study examines the effects of transverse electric fields and axial magnetic fields on various physical properties, such as band structure, density of states (DOS), heat capacity, magnetic susceptibility, and other thermoelectric properties. BPNTs consistently show semiconducting properties with a nearly 1 eV direct band gap. The electronic properties of BPNTs are significantly affected by applied electric field, which at very strong strengths can induce a semiconducting to metallic phase transition. In contrast, the magnetic field leads to the splitting of energy bands, especially around the Fermi level. The DOS also changes with the electric field, including variations in the position, intensity, and number of DOS peaks. The thermal properties and thermoelectric performance of BPNTs are temperature-dependent. Increasing of excited electrons thermal energy cause more occupation of high energy levels in the conduction bands. The electric field further enhances the thermal properties of BPNTs by modifying their electronic properties and reducing the band gap. Stronger electric fields cause a noticeable enhancement in the BPNTs thermal properties because it is increasing the concentration of excited charge carriers. This aspect is crucial for improving the thermoelectric efficiency of BPNTs, making them more competitive for practical applications.
{"title":"Modulation of electronic and thermal properties of boron phosphide nanotubes under electric and magnetic fields","authors":"Nooshin Rashidi , Rostam Moradian","doi":"10.1016/j.physe.2024.116125","DOIUrl":"10.1016/j.physe.2024.116125","url":null,"abstract":"<div><div>This work theoretically investigates the thermoelectric properties of boron phosphide nanotubes (BPNTs) using the tight-binding model, Green function method, and Kubo formalism, focusing on a zigzag BPNT with indices (20, 0). The tight binding parameters obtained by matching its band structure with calculated density functional theory band structure. The study examines the effects of transverse electric fields and axial magnetic fields on various physical properties, such as band structure, density of states (DOS), heat capacity, magnetic susceptibility, and other thermoelectric properties. BPNTs consistently show semiconducting properties with a nearly 1 eV direct band gap. The electronic properties of BPNTs are significantly affected by applied electric field, which at very strong strengths can induce a semiconducting to metallic phase transition. In contrast, the magnetic field leads to the splitting of energy bands, especially around the Fermi level. The DOS also changes with the electric field, including variations in the position, intensity, and number of DOS peaks. The thermal properties and thermoelectric performance of BPNTs are temperature-dependent. Increasing of excited electrons thermal energy cause more occupation of high energy levels in the conduction bands. The electric field further enhances the thermal properties of BPNTs by modifying their electronic properties and reducing the band gap. Stronger electric fields cause a noticeable enhancement in the BPNTs thermal properties because it is increasing the concentration of excited charge carriers. This aspect is crucial for improving the thermoelectric efficiency of BPNTs, making them more competitive for practical applications.</div></div>","PeriodicalId":20181,"journal":{"name":"Physica E-low-dimensional Systems & Nanostructures","volume":"165 ","pages":"Article 116125"},"PeriodicalIF":2.9,"publicationDate":"2024-10-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142534820","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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}
This work presents a multifunctional metastructure (MS) which realizes linear to circular polarization conversion and sensing function based on quasi-bound states in the continuum (quasi-BIC). MS is made of silicon dioxide as substrate, and silicon as surface material, by etching cross holes and square holes on it to form a 2×2 structure, through the transmission of terahertz (THz) band, to form an ultrahigh quality factor (Q-factor), and realize the conversion of linearly polarized waves to circularly polarized ones. At 178.190 THz, it achieves a Q value of 2969, and in the range 178.193 TH to 178.200 THz, the axial ratio (AR) is less than 3 dB and the insertion loss is less than 0.0001. In addition, by changing the permittivity of the surrounding environment, the minimum of the output wave will produce a good linear frequency shift. Using this feature, the given device can also be used as a dielectric constant sensor to detect air quality. The device has a sensing sensitivity (S) of 6.415 THz RIU−1 and a figure of merit (FOM) of 106.9. The parameters (H, w2, L2, g2), incidence angle (θ) and the polarization angle (φ) are discussed. The effects of different parameters on the Q-factor and AR were analyzed, which helped to select the optimal parameters. The design can also be used in communication and biosensing.
{"title":"A metasurface for linear-to-circular polarization conversion and sensing based on quasi-BIC","authors":"Fa-Zhan Liu, Si-Yuan Liao, Qi-Juan Li, Jing-Wei Huang, Hai-Feng Zhang","doi":"10.1016/j.physe.2024.116128","DOIUrl":"10.1016/j.physe.2024.116128","url":null,"abstract":"<div><div>This work presents a multifunctional metastructure (MS) which realizes linear to circular polarization conversion and sensing function based on quasi-bound states in the continuum (quasi-BIC). MS is made of silicon dioxide as substrate, and silicon as surface material, by etching cross holes and square holes on it to form a 2×2 structure, through the transmission of terahertz (THz) band, to form an ultrahigh quality factor (<em>Q</em>-factor), and realize the conversion of linearly polarized waves to circularly polarized ones. At 178.190 THz, it achieves a <em>Q</em> value of 2969, and in the range 178.193 TH to 178.200 THz, the axial ratio (AR) is less than 3 dB and the insertion loss is less than 0.0001. In addition, by changing the permittivity of the surrounding environment, the minimum of the output wave will produce a good linear frequency shift. Using this feature, the given device can also be used as a dielectric constant sensor to detect air quality. The device has a sensing sensitivity (<em>S</em>) of 6.415 THz RIU<sup>−1</sup> and a figure of merit (<em>FOM</em>) of 106.9. The parameters (<em>H</em>, <em>w</em><sub>2</sub>, <em>L</em><sub>2</sub>, <em>g</em><sub>2</sub>), incidence angle (<em>θ</em>) and the polarization angle (<em>φ</em>) are discussed. The effects of different parameters on the <em>Q</em>-factor and AR were analyzed, which helped to select the optimal parameters. The design can also be used in communication and biosensing.</div></div>","PeriodicalId":20181,"journal":{"name":"Physica E-low-dimensional Systems & Nanostructures","volume":"165 ","pages":"Article 116128"},"PeriodicalIF":2.9,"publicationDate":"2024-10-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142425336","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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 : 2024-10-10DOI: 10.1016/j.physe.2024.116129
Shao-Chong Yin , Jing-Xin Yu , Xiu-Ying Liu , Xiao-Dong Li , Jing Chang
Exploring the attainment of half-metallic behavior in two-dimensional (2D) materials through external perturbations is a popular area of current research. In this work, we demonstrate, using first-principles calculations, that bilayer NiI2 (bi-NiI2) is an A-type antiferromagnetic (AFM) semiconductor with an indirect bandgap of 0.86 eV, with the most stable configuration being the AB stacking mode. Upon the application of a vertical electric field, the material transforms from its original semiconducting state into a half-metallic state. Moreover, the spin polarization reverses its orientation whenever the direction of the electric field is altered. This intriguing behavior has inspired us to design a spintronic device based on the A-type AFM bi-NiI2. By employing nonequilibrium Green's function (NEGF) combined with density functional theory (DFT) calculations, we find that the device achieves ON/OFF switching by applying vertical electric fields in parallel or anti-parallel configurations in the two leads. The device displays 100 % spin polarization in the parallel configuration (PC) scenario, driven by bias voltage or temperature differences. Utilizing either the parallel or antiparallel configuration (APC) for ON/OFF switching enables the device to exhibit tunneling magnetoresistance (TMR) of up to 1.45 × 1010 % due to bias voltage and up to 1011 % thermal TMR arising from temperature differences between the leads. These findings highlight the potential of NiI2 and A-type AFM bilayers in the design of spintronic devices.
探索通过外部扰动在二维（2D）材料中实现半金属行为是当前研究的一个热门领域。在这项研究中，我们利用第一原理计算证明，双层 NiI2（bi-NiI2）是一种 A 型反铁磁性（AFM）半导体，其间接带隙为 0.86 eV，最稳定的构型是 AB 堆积模式。当施加垂直电场时，这种材料会从原来的半导体状态转变为半金属状态。此外，只要改变电场方向，自旋极化就会反转方向。这一引人入胜的行为启发我们设计一种基于 A 型 AFM 双 NiI2 的自旋电子器件。通过采用非平衡格林函数（NEGF）和密度泛函理论（DFT）计算，我们发现该器件可以通过在两条引线上施加平行或反平行配置的垂直电场来实现导通/关断开关。在平行配置（PC）情况下，该器件在偏置电压或温差的驱动下显示出 100% 的自旋极化。利用平行或反平行配置（APC）进行导通/关断开关，可使器件因偏置电压而表现出高达 1.45 × 1010 % 的隧穿磁阻（TMR），因引线之间的温差而表现出高达 1011 % 的热 TMR。这些发现凸显了 NiI2 和 A 型 AFM 双层膜在设计自旋电子器件方面的潜力。
{"title":"Design of spintronic devices based on adjustable half-metallicity induced by electric field in A-type antiferromagnetic bilayer NiI2","authors":"Shao-Chong Yin , Jing-Xin Yu , Xiu-Ying Liu , Xiao-Dong Li , Jing Chang","doi":"10.1016/j.physe.2024.116129","DOIUrl":"10.1016/j.physe.2024.116129","url":null,"abstract":"<div><div>Exploring the attainment of half-metallic behavior in two-dimensional (2D) materials through external perturbations is a popular area of current research. In this work, we demonstrate, using first-principles calculations, that bilayer NiI<sub>2</sub> (bi-NiI<sub>2</sub>) is an A-type antiferromagnetic (AFM) semiconductor with an indirect bandgap of 0.86 eV, with the most stable configuration being the AB stacking mode. Upon the application of a vertical electric field, the material transforms from its original semiconducting state into a half-metallic state. Moreover, the spin polarization reverses its orientation whenever the direction of the electric field is altered. This intriguing behavior has inspired us to design a spintronic device based on the A-type AFM bi-NiI<sub>2</sub>. By employing nonequilibrium Green's function (NEGF) combined with density functional theory (DFT) calculations, we find that the device achieves ON/OFF switching by applying vertical electric fields in parallel or anti-parallel configurations in the two leads. The device displays 100 % spin polarization in the parallel configuration (PC) scenario, driven by bias voltage or temperature differences. Utilizing either the parallel or antiparallel configuration (APC) for ON/OFF switching enables the device to exhibit tunneling magnetoresistance (TMR) of up to 1.45 × 10<sup>10</sup> % due to bias voltage and up to 10<sup>11</sup> % thermal TMR arising from temperature differences between the leads. These findings highlight the potential of NiI<sub>2</sub> and A-type AFM bilayers in the design of spintronic devices.</div></div>","PeriodicalId":20181,"journal":{"name":"Physica E-low-dimensional Systems & Nanostructures","volume":"165 ","pages":"Article 116129"},"PeriodicalIF":2.9,"publicationDate":"2024-10-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142433333","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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 : 2024-10-09DOI: 10.1016/j.physe.2024.116126
Mehmet Batı
We examine the resonant tunneling properties of the laser-dressed hyperbolic Pöschl-Teller double quantum barrier structure. We use the non-equilibrium Green's function method to investigate structure parameters and electric field bias on the transmission properties of the system. The transmission probabilities and resonance energy levels are significantly influenced by the well widths and barrier heights. The barrier height increases, resonance energy levels shift toward higher values, and the resonance peak width narrows, leading to sharper and more selective tunneling behavior. Our results show that increasing the electric field bias leads to a decrease in the transmission probability at the first resonance peak, but this effect is not as strong for the subsequent peaks. Moreover, we find that changes in the laser field's parameter and structure parameters allow for fine control over the electronic spectra, allowing for modifications like red or blue shifts based on particular needs. The significance of comprehending the interaction among structural factors, external fields, and transmission qualities in quantum barrier structures is highlighted by our research, providing valuable information for the development and enhancement of electronic and optoelectronic systems with customized functionality. Our findings show the laser field has a considerable impact on resonant tunneling properties, opening the door to new device applications.
{"title":"Resonant tunneling properties of laser dressed hyperbolic Pöschl-Teller double barrier potential","authors":"Mehmet Batı","doi":"10.1016/j.physe.2024.116126","DOIUrl":"10.1016/j.physe.2024.116126","url":null,"abstract":"<div><div>We examine the resonant tunneling properties of the laser-dressed hyperbolic Pöschl-Teller double quantum barrier structure. We use the non-equilibrium Green's function method to investigate structure parameters and electric field bias on the transmission properties of the system. The transmission probabilities and resonance energy levels are significantly influenced by the well widths and barrier heights. The barrier height increases, resonance energy levels shift toward higher values, and the resonance peak width narrows, leading to sharper and more selective tunneling behavior. Our results show that increasing the electric field bias leads to a decrease in the transmission probability at the first resonance peak, but this effect is not as strong for the subsequent peaks. Moreover, we find that changes in the laser field's parameter and structure parameters allow for fine control over the electronic spectra, allowing for modifications like red or blue shifts based on particular needs. The significance of comprehending the interaction among structural factors, external fields, and transmission qualities in quantum barrier structures is highlighted by our research, providing valuable information for the development and enhancement of electronic and optoelectronic systems with customized functionality. Our findings show the laser field has a considerable impact on resonant tunneling properties, opening the door to new device applications.</div></div>","PeriodicalId":20181,"journal":{"name":"Physica E-low-dimensional Systems & Nanostructures","volume":"165 ","pages":"Article 116126"},"PeriodicalIF":2.9,"publicationDate":"2024-10-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142425333","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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}
Electronic properties of a neutral donor confined in a coupled quantum dot-ring covered by a matrix were calculated using the finite element method under the effective mass and the envelope function approximations. The proposed model is set up to fit a realistic coupled quantum dot-ring geometry revealed by atomic force microscopy images. The results show that the energy levels and the transition energies in the presence of an electric field strongly depend on the donor center’s angular position. Furthermore, the total optical absorption coefficient is calculated within the two-level approximation and the matrix density formalism. The absorption spectrum shows that the system can be tuned between 5 and . Also, an optical transparency effect for different configurations characterized by specific donor center’s angular positions and electric field values is seen. Finally, a novel redshift is observed when the sample temperature increases.
{"title":"Neutral donors confined in semiconductor coupled quantum dot-rings: Position-dependent properties and optical transparency phenomenon","authors":"N. Hernández , R.A. López-Doria , Y.A. Suaza , M.R. Fulla","doi":"10.1016/j.physe.2024.116122","DOIUrl":"10.1016/j.physe.2024.116122","url":null,"abstract":"<div><div>Electronic properties of a neutral donor confined in a <span><math><mi>GaAs</mi></math></span> coupled quantum dot-ring covered by a <span><math><mrow><msub><mrow><mi>Al</mi></mrow><mrow><mn>0</mn><mo>.</mo><mn>3</mn></mrow></msub><msub><mrow><mi>Ga</mi></mrow><mrow><mn>0</mn><mo>.</mo><mn>7</mn></mrow></msub><mi>As</mi></mrow></math></span> matrix were calculated using the finite element method under the effective mass and the envelope function approximations. The proposed model is set up to fit a realistic coupled quantum dot-ring geometry revealed by atomic force microscopy images. The results show that the energy levels and the transition energies in the presence of an electric field strongly depend on the donor center’s angular position. Furthermore, the total optical absorption coefficient is calculated within the two-level approximation and the matrix density formalism. The absorption spectrum shows that the system can be tuned between 5 and <span><math><mrow><mn>30</mn><mspace></mspace><mi>meV</mi></mrow></math></span>. Also, an optical transparency effect for different configurations characterized by specific donor center’s angular positions and electric field values is seen. Finally, a novel redshift is observed when the sample temperature increases.</div></div>","PeriodicalId":20181,"journal":{"name":"Physica E-low-dimensional Systems & Nanostructures","volume":"165 ","pages":"Article 116122"},"PeriodicalIF":2.9,"publicationDate":"2024-10-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142425334","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The atomically thin layers of transition-metal dichalcogenide (TMDC) materials have garnered considerable attention due to their exceptional electrical, optical, mechanical, and thermal properties. Hence, it is important to investigate the mechanism of their excellent properties. In this paper, the study is focused on the correlation between valence electron structures (VESs) and mechanical as well as thermal properties of graphene and MX2 (M = Mo, W; X = S, Se, Te) for revealing their essential mechanisms of properties with an empirical electron theory (EET). A model of Young's modulus is built for the monolayer graphene and MX2 (M = Mo, W; X = S, Se, Te) based on the VES, which has been verified by the observed ones of elements in the 4th to 6th periods in the periodic table of elements. The calculated bond lengths and mechanical and thermal properties of graphene and MX2 are in good agreement with experimental ones. The study reveals that the thermal and mechanical properties of MX2 strongly depend on their valence electron structures. It shows that the melting point, cohesive energy, thermal conductivity, and Young's modulus are modulated by covalence electron pair nA, the averaged covalence electron per atom nc/atom, covalence electron pair nA and linear density of covalent electron on the strongest bond ρl, respectively. The study helps explain the thermal and mechanical properties of two-dimensional (2D) materials and also supplies a reference for their design with high performance by modulating their valence electron structures.
{"title":"Correlation of Valence electron structure and properties of monolayer graphene and MX2 (M=Mo, W; X=S, Se, Te): Empirical Electron Theory (EET) investigation","authors":"Xinze Wang, Yongquan Guo, Boyang Li, Yichen Feng, Wei Tang","doi":"10.1016/j.physe.2024.116124","DOIUrl":"10.1016/j.physe.2024.116124","url":null,"abstract":"<div><div>The atomically thin layers of transition-metal dichalcogenide (TMDC) materials have garnered considerable attention due to their exceptional electrical, optical, mechanical, and thermal properties. Hence, it is important to investigate the mechanism of their excellent properties. In this paper, the study is focused on the correlation between valence electron structures (VESs) and mechanical as well as thermal properties of graphene and MX<sub>2</sub> (M = Mo, W; X = S, Se, Te) for revealing their essential mechanisms of properties with an empirical electron theory (EET). A model of Young's modulus is built for the monolayer graphene and MX<sub>2</sub> (M = Mo, W; X = S, Se, Te) based on the VES, which has been verified by the observed ones of elements in the 4th to 6th periods in the periodic table of elements. The calculated bond lengths and mechanical and thermal properties of graphene and MX<sub>2</sub> are in good agreement with experimental ones. The study reveals that the thermal and mechanical properties of MX<sub>2</sub> strongly depend on their valence electron structures. It shows that the melting point, cohesive energy, thermal conductivity, and Young's modulus are modulated by covalence electron pair <em>n</em><sub><em>A</em></sub>, the averaged covalence electron per atom <em>n</em><sub><em>c</em></sub>/atom, covalence electron pair <em>n</em><sub><em>A</em></sub> and linear density of covalent electron on the strongest bond <em>ρ</em><sub><em>l</em></sub>, respectively. The study helps explain the thermal and mechanical properties of two-dimensional (2D) materials and also supplies a reference for their design with high performance by modulating their valence electron structures.</div></div>","PeriodicalId":20181,"journal":{"name":"Physica E-low-dimensional Systems & Nanostructures","volume":"165 ","pages":"Article 116124"},"PeriodicalIF":2.9,"publicationDate":"2024-10-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142425335","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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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