Pub Date : 2025-10-01Epub Date: 2025-07-29DOI: 10.1016/j.physe.2025.116341
Jiaqi Zhang , Fangfang Li , Jiakang Li , Wenhui Han , Guangwei Wang , Kaixing Zhu , Yan Xu , Peng Wang
The structural and electronic properties of monolayer 1T-PtSe2 doped with various single transition metal (TM) atoms (Co, Ni, Cu, Mo, Rh, Pd, Ir, and Au) at selenium vacancy sites, along with their interaction with NO2 gas molecules, have been systematically investigated using density functional theory (DFT). TM doping notably enhances the chemical reactivity and alters the electronic structure of PtSe2, as reflected in stronger NO2 adsorption, increased charge transfer, and the emergence of impurity states near the Fermi level. These effects are primarily attributed to the introduction of TM nd-orbitals, which facilitate molecular activation. Among the doped systems, Pd-PtSe2 demonstrates superior gas sensing performance with a short recovery time in the 400–500 K range. These findings provide valuable theoretical guidance for designing high-efficiency gas sensors based on TM-doped PtSe2 monolayers.
{"title":"Single transition-metal atom doping enhances NO2 adsorption on 1T-PtSe2 monolayer","authors":"Jiaqi Zhang , Fangfang Li , Jiakang Li , Wenhui Han , Guangwei Wang , Kaixing Zhu , Yan Xu , Peng Wang","doi":"10.1016/j.physe.2025.116341","DOIUrl":"10.1016/j.physe.2025.116341","url":null,"abstract":"<div><div>The structural and electronic properties of monolayer 1T-PtSe<sub>2</sub> doped with various single transition metal (TM) atoms (Co, Ni, Cu, Mo, Rh, Pd, Ir, and Au) at selenium vacancy sites, along with their interaction with NO<sub>2</sub> gas molecules, have been systematically investigated using density functional theory (DFT). TM doping notably enhances the chemical reactivity and alters the electronic structure of PtSe<sub>2</sub>, as reflected in stronger NO<sub>2</sub> adsorption, increased charge transfer, and the emergence of impurity states near the Fermi level. These effects are primarily attributed to the introduction of TM nd-orbitals, which facilitate molecular activation. Among the doped systems, Pd-PtSe<sub>2</sub> demonstrates superior gas sensing performance with a short recovery time in the 400–500 K range. These findings provide valuable theoretical guidance for designing high-efficiency gas sensors based on TM-doped PtSe<sub>2</sub> monolayers.</div></div>","PeriodicalId":20181,"journal":{"name":"Physica E-low-dimensional Systems & Nanostructures","volume":"174 ","pages":"Article 116341"},"PeriodicalIF":2.9,"publicationDate":"2025-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144771003","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 : 2025-10-01Epub Date: 2025-08-14DOI: 10.1016/j.physe.2025.116353
K. Chauhan , D. Banerjee, V.P. Shrivastava
The work reports the synthesis of silver doped graphitic carbon nitride (GCN) using urea as precursor. Both the pure and doped samples were characterized by X-ray diffraction (XRD), Field emission scanning electron microscope (FESEM), Energy-dispersive X-ray spectroscopy (EDX) and Fourier transformed infrared (FTIR) spectroscopy analysis.
XRD confirmed the proper phase formation of the samples with preferential growth along (002) direction whereas FESEM shows the growth of chip-like morphologies with high yield, EDX analysed the stoichiometric ratio of sample and FTIR revealed the different vibrational energy level present.
The efficacies of the samples in degrading Bengal Rose under UV light irradiation was studied. The results demonstrated that the doped samples exhibited excellent dye removal performance, achieving an efficiency of more than 85 % within just 40 min. Not only that, here the electrical energy per order as well as degradation turnover of both samples were calculated and shown that the doped sample has much higher promises compared to pure GCN. Especially, degradation turnover came out to be over 95 % for the doped sample with an exposure time of just 10 min.
When reaction kinetics was studied it is seen that the reaction mainly followed 1st order kinetics with regression coefficient almost unity. Here also doped sample showed faster kinetics with reaction constant value 0.050/minute.
It has been concluded that dopant create intermediate energy states where charge carrier can rest prolonging electron hole pair recombination which in turn facilitate the interaction with dyes and thus enhancing its removal performance.
{"title":"Solid state synthesis of silver doped graphitic carbon nitride and its efficacy in removing textile dyes","authors":"K. Chauhan , D. Banerjee, V.P. Shrivastava","doi":"10.1016/j.physe.2025.116353","DOIUrl":"10.1016/j.physe.2025.116353","url":null,"abstract":"<div><div>The work reports the synthesis of silver doped graphitic carbon nitride (GCN) using urea as precursor. Both the pure and doped samples were characterized by X-ray diffraction (XRD), Field emission scanning electron microscope (FESEM), Energy-dispersive X-ray spectroscopy (EDX) and Fourier transformed infrared (FTIR) spectroscopy analysis.</div><div>XRD confirmed the proper phase formation of the samples with preferential growth along (002) direction whereas FESEM shows the growth of chip-like morphologies with high yield, EDX analysed the stoichiometric ratio of sample and FTIR revealed the different vibrational energy level present.</div><div>The efficacies of the samples in degrading Bengal Rose under UV light irradiation was studied. The results demonstrated that the doped samples exhibited excellent dye removal performance, achieving an efficiency of more than 85 % within just 40 min. Not only that, here the electrical energy per order as well as degradation turnover of both samples were calculated and shown that the doped sample has much higher promises compared to pure GCN. Especially, degradation turnover came out to be over 95 % for the doped sample with an exposure time of just 10 min.</div><div>When reaction kinetics was studied it is seen that the reaction mainly followed 1st order kinetics with regression coefficient almost unity. Here also doped sample showed faster kinetics with reaction constant value 0.050/minute.</div><div>It has been concluded that dopant create intermediate energy states where charge carrier can rest prolonging electron hole pair recombination which in turn facilitate the interaction with dyes and thus enhancing its removal performance.</div></div>","PeriodicalId":20181,"journal":{"name":"Physica E-low-dimensional Systems & Nanostructures","volume":"174 ","pages":"Article 116353"},"PeriodicalIF":2.9,"publicationDate":"2025-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144864403","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 : 2025-10-01Epub Date: 2025-08-30DOI: 10.1016/j.physe.2025.116352
Yajun Wei, J. Wang
We investigate the possibility of a Chern insulator phase transition in two-dimensional altermagnetic (AM) metals by incorporating the effects of Rashba spin–orbit coupling (RSOC) and an additional exchange field. We present a phase diagram of the system as a function of the AM and exchange field strengths, and demonstrate that when the AM exchange strength exceeds a critical value of the exchange field, the system shows a nonzero Chern number. Moreover, we find that not only do the RSOC and exchange field significantly affect the topological properties, but the AM exchange energy and band energy also play essential roles. Specifically, when the AM exchange energy exceeds the AM band energy and the spin-momentum coupling exhibits clear valley separation, a bulk energy gap opens, and the system transitions into the quantum anomalous Hall insulator regime. Conversely, when the AM exhibits only anisotropic spin-momentum coupling, the system retains the same Chern number but lacks corresponding chiral edge states. We further compute the transport properties of a valley-dependent AM ribbon structure, confirming the existence of possible chiral edge states and their robustness.
{"title":"Chern insulator phase transition in valley-dependent altermagnet","authors":"Yajun Wei, J. Wang","doi":"10.1016/j.physe.2025.116352","DOIUrl":"10.1016/j.physe.2025.116352","url":null,"abstract":"<div><div>We investigate the possibility of a Chern insulator phase transition in two-dimensional altermagnetic (AM) metals by incorporating the effects of Rashba spin–orbit coupling (RSOC) and an additional exchange field. We present a phase diagram of the system as a function of the AM and exchange field strengths, and demonstrate that when the AM exchange strength exceeds a critical value of the exchange field, the system shows a nonzero Chern number. Moreover, we find that not only do the RSOC and exchange field significantly affect the topological properties, but the AM exchange energy and band energy also play essential roles. Specifically, when the AM exchange energy exceeds the AM band energy and the spin-momentum coupling exhibits clear valley separation, a bulk energy gap opens, and the system transitions into the quantum anomalous Hall insulator regime. Conversely, when the AM exhibits only anisotropic spin-momentum coupling, the system retains the same Chern number but lacks corresponding chiral edge states. We further compute the transport properties of a valley-dependent AM ribbon structure, confirming the existence of possible chiral edge states and their robustness.</div></div>","PeriodicalId":20181,"journal":{"name":"Physica E-low-dimensional Systems & Nanostructures","volume":"174 ","pages":"Article 116352"},"PeriodicalIF":2.9,"publicationDate":"2025-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144922305","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 : 2025-10-01Epub Date: 2025-08-30DOI: 10.1016/j.physe.2025.116357
Jacob Wekalao , Mahmood Basil A. AL-Rawi , Ahmed Zohier Ahmed Elhendi , Ahmed Mehaney , Hussein A. Elsayed , Mostafa R. Abukhadra , Haifa A. Alqhtani , Amuthakkannan Rajakannu
In this study, we propose an innovative biosensor design that incorporates multiple resonators specifically engineered for detecting carcinoembryonic antigen (CEA). The biosensor integrates a unique combination of materials, including MXene, black phosphorus, and graphene, arranged in a hybrid configuration. The design consists of a centrally positioned circular MXene resonator encircled by a square ring of black phosphorus, complemented by four gold circular resonators. These components are assembled on a silicon dioxide substrate. A comprehensive performance evaluation was conducted across the terahertz spectrum (0.1–1.0 THz) using finite element method modeling in COMSOL Multiphysics 6.2. The biosensor demonstrated impressive metrics, including a maximum sensitivity of 811 GHz RIU−1, a figure of merit of 14.479 RIU−1, and a quality factor of 6.946. When tested with varying CEA concentrations ranging from 0 to 5 ng/mL, the device maintained stable and reliable operation. The transmission characteristics revealed systematic frequency variations from 0.389 THz to 0.382 THz. Additionally, a machine learning approach based on stacking ensemble regression was implemented to optimize sensor parameters. This computational strategy delivered outstanding predictive performance, achieving near-perfect accuracy across most operational variables. The biosensor's combination of high sensitivity, compact design, and reliable functionality positions it as a promising technology for early cancer screening and patient monitoring applications.
{"title":"Terahertz multi-resonator refractive index sensor with graphene and MXene integration for cancer biomarker analysis","authors":"Jacob Wekalao , Mahmood Basil A. AL-Rawi , Ahmed Zohier Ahmed Elhendi , Ahmed Mehaney , Hussein A. Elsayed , Mostafa R. Abukhadra , Haifa A. Alqhtani , Amuthakkannan Rajakannu","doi":"10.1016/j.physe.2025.116357","DOIUrl":"10.1016/j.physe.2025.116357","url":null,"abstract":"<div><div>In this study, we propose an innovative biosensor design that incorporates multiple resonators specifically engineered for detecting carcinoembryonic antigen (CEA). The biosensor integrates a unique combination of materials, including MXene, black phosphorus, and graphene, arranged in a hybrid configuration. The design consists of a centrally positioned circular MXene resonator encircled by a square ring of black phosphorus, complemented by four gold circular resonators. These components are assembled on a silicon dioxide substrate. A comprehensive performance evaluation was conducted across the terahertz spectrum (0.1–1.0 THz) using finite element method modeling in COMSOL Multiphysics 6.2. The biosensor demonstrated impressive metrics, including a maximum sensitivity of 811 GHz RIU<sup>−1</sup>, a figure of merit of 14.479 RIU<sup>−1</sup>, and a quality factor of 6.946. When tested with varying CEA concentrations ranging from 0 to 5 ng/mL, the device maintained stable and reliable operation. The transmission characteristics revealed systematic frequency variations from 0.389 THz to 0.382 THz. Additionally, a machine learning approach based on stacking ensemble regression was implemented to optimize sensor parameters. This computational strategy delivered outstanding predictive performance, achieving near-perfect accuracy across most operational variables. The biosensor's combination of high sensitivity, compact design, and reliable functionality positions it as a promising technology for early cancer screening and patient monitoring applications.</div></div>","PeriodicalId":20181,"journal":{"name":"Physica E-low-dimensional Systems & Nanostructures","volume":"174 ","pages":"Article 116357"},"PeriodicalIF":2.9,"publicationDate":"2025-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144922306","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 : 2025-10-01Epub Date: 2025-07-24DOI: 10.1016/j.physe.2025.116338
Xinyi Shan , Hongxu Liu , Bingjie Ye , Leyang Qian , Xuekun Hong , Yushen Liu , Irina N. Parkhomenko , Fadei F. Komarov , Guofeng Yang
Low-dimensional halide perovskite semiconductor materials have attracted much attention from researchers due to their unique physicochemical properties that distinguish them from conventional semiconductor materials, but most of the current low-dimensional metal halide perovskite materials contain elemental lead, which hinders their large-scale use. Here, we introduce a two-dimensional lead-free perovskite Cs3Sb2I9 and further construct a Cs3Sb2I9/InX (X = S, Se) heterostructure based on the density-functional theory to investigate its electrical and optical properties. The magnitude of van der Waals forces between the layers of the heterostructure was analyzed by calculating the variation of the binding energy with the layer spacing. The projected energy bands and projected density of states of the heterostructures show that both heterostructures have a type-II energy band alignment at the interface. The calculated differential charge densities show the charge transfer process in the heterostructures, and the results indicate that the charge transfer mainly occurs at the interface and the electrons mainly accumulate in the InX layer. In addition, the light absorption coefficient and dielectric function of the heterostructure are significantly improved compared with those of the isolated material. Especially in the ultraviolet (UV) region, the peak absorption coefficient of the heterojunction can reach 4.16 × 105 cm−1. Subsequently, the response behavior of the heterostructure devices to different wavelengths of incident light was investigated, and the two devices showed peak responsivity of 21 mA/W and 34 mA/W at 3.4 eV and 3.95 eV, respectively. The results of our study suggest that the Cs3Sb2I9/InX (X = S, Se) heterostructure has the potential to be applied in UV photodetector devices.
{"title":"Optoelectronic properties of two-dimensional lead-free perovskite Cs3Sb2I9/InX (X = S, Se) van der Waals heterostructures","authors":"Xinyi Shan , Hongxu Liu , Bingjie Ye , Leyang Qian , Xuekun Hong , Yushen Liu , Irina N. Parkhomenko , Fadei F. Komarov , Guofeng Yang","doi":"10.1016/j.physe.2025.116338","DOIUrl":"10.1016/j.physe.2025.116338","url":null,"abstract":"<div><div>Low-dimensional halide perovskite semiconductor materials have attracted much attention from researchers due to their unique physicochemical properties that distinguish them from conventional semiconductor materials, but most of the current low-dimensional metal halide perovskite materials contain elemental lead, which hinders their large-scale use. Here, we introduce a two-dimensional lead-free perovskite Cs<sub>3</sub>Sb<sub>2</sub>I<sub>9</sub> and further construct a Cs<sub>3</sub>Sb<sub>2</sub>I<sub>9</sub>/InX (X = S, Se) heterostructure based on the density-functional theory to investigate its electrical and optical properties. The magnitude of van der Waals forces between the layers of the heterostructure was analyzed by calculating the variation of the binding energy with the layer spacing. The projected energy bands and projected density of states of the heterostructures show that both heterostructures have a type-II energy band alignment at the interface. The calculated differential charge densities show the charge transfer process in the heterostructures, and the results indicate that the charge transfer mainly occurs at the interface and the electrons mainly accumulate in the InX layer. In addition, the light absorption coefficient and dielectric function of the heterostructure are significantly improved compared with those of the isolated material. Especially in the ultraviolet (UV) region, the peak absorption coefficient of the heterojunction can reach 4.16 × 10<sup>5</sup> cm<sup>−1</sup>. Subsequently, the response behavior of the heterostructure devices to different wavelengths of incident light was investigated, and the two devices showed peak responsivity of 21 mA/W and 34 mA/W at 3.4 eV and 3.95 eV, respectively. The results of our study suggest that the Cs<sub>3</sub>Sb<sub>2</sub>I<sub>9</sub>/InX (X = S, Se) heterostructure has the potential to be applied in UV photodetector devices.</div></div>","PeriodicalId":20181,"journal":{"name":"Physica E-low-dimensional Systems & Nanostructures","volume":"174 ","pages":"Article 116338"},"PeriodicalIF":2.9,"publicationDate":"2025-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144749031","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}
<div><div>We systematically investigate the spin Nernst effect (SNE) of surface states in three-dimensional topological insulator film under a perpendicular magnetic field. The spin Nernst coefficient <span><math><msub><mrow><mi>N</mi></mrow><mrow><mi>s</mi></mrow></msub></math></span> of surface states, which are lie in the quantum spin Hall regime (QSH), quantum anomalous Hall regime (QAH), and quantum pseudospin Hall regime (QPH), is theoretically calculated by using the Non-equilibrium Green’s function method combined with the square lattice model. Regardless of the presence of a magnetic field, SNE will occur in the system because it primarily arises from spin–orbit coupling. When the Fermi energy <span><math><msub><mrow><mi>E</mi></mrow><mrow><mi>F</mi></mrow></msub></math></span> crosses the discrete transverse channels, <span><math><msub><mrow><mi>N</mi></mrow><mrow><mi>s</mi></mrow></msub></math></span> exhibits a pronounced peak. The height of peak strongly depends on the temperature, decreasing with increasing temperature. In the QPH regime, <span><math><msub><mrow><mi>N</mi></mrow><mrow><mi>s</mi></mrow></msub></math></span> is an even function of <span><math><msub><mrow><mi>E</mi></mrow><mrow><mi>F</mi></mrow></msub></math></span> with <span><math><mrow><msub><mrow><mi>N</mi></mrow><mrow><mi>s</mi></mrow></msub><mrow><mo>(</mo><mo>−</mo><msub><mrow><mi>E</mi></mrow><mrow><mi>F</mi></mrow></msub><mo>)</mo></mrow><mo>=</mo><msub><mrow><mi>N</mi></mrow><mrow><mi>s</mi></mrow></msub><mrow><mo>(</mo><msub><mrow><mi>E</mi></mrow><mrow><mi>F</mi></mrow></msub><mo>)</mo></mrow></mrow></math></span> without applying a magnetic field. However, this the symmetrical property is destroyed when a magnetic field is applied. In the QSH and QAH regimes, <span><math><msub><mrow><mi>N</mi></mrow><mrow><mi>s</mi></mrow></msub></math></span> is also an even function of <span><math><msub><mrow><mi>E</mi></mrow><mrow><mi>F</mi></mrow></msub></math></span> in magnetic field <span><math><mrow><mi>ϕ</mi><mo>=</mo><mn>0</mn><mo>.</mo><mn>0</mn></mrow></math></span>. When a magnetic field is applied, <span><math><msub><mrow><mi>N</mi></mrow><mrow><mi>s</mi></mrow></msub></math></span> of QSH regime retains this symmetrical property due to protection from time-reversal symmetry. But the symmetrical property <span><math><mrow><msub><mrow><mi>N</mi></mrow><mrow><mi>s</mi></mrow></msub><mrow><mo>(</mo><mo>−</mo><msub><mrow><mi>E</mi></mrow><mrow><mi>F</mi></mrow></msub><mo>)</mo></mrow><mo>=</mo><msub><mrow><mi>N</mi></mrow><mrow><mi>s</mi></mrow></msub><mrow><mo>(</mo><msub><mrow><mi>E</mi></mrow><mrow><mi>F</mi></mrow></msub><mo>)</mo></mrow></mrow></math></span> is broken in the QAH regime. This is because that the combined influence of the exchange field and magnetic field breaks time-reversal symmetry, leading to the peak structure of <span><math><msub><mrow><mi>N</mi></mrow><mrow><mi>s</mi></mrow></msub></math></span> to reverse around <span><math><mrow><msub
{"title":"Controllable spin Nernst effect of surface states in three-dimensional topological insulator film","authors":"Xin-Ning Li, Ning-Xuan Yang, Rui Wang, Chun-Yan Song, Hui Liao, Ting-Ting Song, Xue-Yan Cheng, Jiu-Ming Wang","doi":"10.1016/j.physe.2025.116331","DOIUrl":"10.1016/j.physe.2025.116331","url":null,"abstract":"<div><div>We systematically investigate the spin Nernst effect (SNE) of surface states in three-dimensional topological insulator film under a perpendicular magnetic field. The spin Nernst coefficient <span><math><msub><mrow><mi>N</mi></mrow><mrow><mi>s</mi></mrow></msub></math></span> of surface states, which are lie in the quantum spin Hall regime (QSH), quantum anomalous Hall regime (QAH), and quantum pseudospin Hall regime (QPH), is theoretically calculated by using the Non-equilibrium Green’s function method combined with the square lattice model. Regardless of the presence of a magnetic field, SNE will occur in the system because it primarily arises from spin–orbit coupling. When the Fermi energy <span><math><msub><mrow><mi>E</mi></mrow><mrow><mi>F</mi></mrow></msub></math></span> crosses the discrete transverse channels, <span><math><msub><mrow><mi>N</mi></mrow><mrow><mi>s</mi></mrow></msub></math></span> exhibits a pronounced peak. The height of peak strongly depends on the temperature, decreasing with increasing temperature. In the QPH regime, <span><math><msub><mrow><mi>N</mi></mrow><mrow><mi>s</mi></mrow></msub></math></span> is an even function of <span><math><msub><mrow><mi>E</mi></mrow><mrow><mi>F</mi></mrow></msub></math></span> with <span><math><mrow><msub><mrow><mi>N</mi></mrow><mrow><mi>s</mi></mrow></msub><mrow><mo>(</mo><mo>−</mo><msub><mrow><mi>E</mi></mrow><mrow><mi>F</mi></mrow></msub><mo>)</mo></mrow><mo>=</mo><msub><mrow><mi>N</mi></mrow><mrow><mi>s</mi></mrow></msub><mrow><mo>(</mo><msub><mrow><mi>E</mi></mrow><mrow><mi>F</mi></mrow></msub><mo>)</mo></mrow></mrow></math></span> without applying a magnetic field. However, this the symmetrical property is destroyed when a magnetic field is applied. In the QSH and QAH regimes, <span><math><msub><mrow><mi>N</mi></mrow><mrow><mi>s</mi></mrow></msub></math></span> is also an even function of <span><math><msub><mrow><mi>E</mi></mrow><mrow><mi>F</mi></mrow></msub></math></span> in magnetic field <span><math><mrow><mi>ϕ</mi><mo>=</mo><mn>0</mn><mo>.</mo><mn>0</mn></mrow></math></span>. When a magnetic field is applied, <span><math><msub><mrow><mi>N</mi></mrow><mrow><mi>s</mi></mrow></msub></math></span> of QSH regime retains this symmetrical property due to protection from time-reversal symmetry. But the symmetrical property <span><math><mrow><msub><mrow><mi>N</mi></mrow><mrow><mi>s</mi></mrow></msub><mrow><mo>(</mo><mo>−</mo><msub><mrow><mi>E</mi></mrow><mrow><mi>F</mi></mrow></msub><mo>)</mo></mrow><mo>=</mo><msub><mrow><mi>N</mi></mrow><mrow><mi>s</mi></mrow></msub><mrow><mo>(</mo><msub><mrow><mi>E</mi></mrow><mrow><mi>F</mi></mrow></msub><mo>)</mo></mrow></mrow></math></span> is broken in the QAH regime. This is because that the combined influence of the exchange field and magnetic field breaks time-reversal symmetry, leading to the peak structure of <span><math><msub><mrow><mi>N</mi></mrow><mrow><mi>s</mi></mrow></msub></math></span> to reverse around <span><math><mrow><msub","PeriodicalId":20181,"journal":{"name":"Physica E-low-dimensional Systems & Nanostructures","volume":"174 ","pages":"Article 116331"},"PeriodicalIF":2.9,"publicationDate":"2025-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144724030","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 : 2025-10-01Epub Date: 2025-07-26DOI: 10.1016/j.physe.2025.116339
M. Kavitha , A. Naifar , A. John Peter , V. Raja
To bridge the gap identified in the current literature, this comprehensive and quantitative investigation examines the tunability of excitonic spectra and light–matter interaction characteristics under hydrostatic pressure, employing three distinct confinement models: Pöschl–Teller, Razavy and Woods–Saxon potentials. The analysis is carried out within the framework of the effective mass approximation, leveraging the density matrix approach to capture the nonlinear behaviour of the resulting optical coefficients. In addition, an in-depth assessment of the parameters influencing the spatial configuration of the confinement potentials was conducted to determine their impact on oscillator strength and radiative lifetime, thereby revealing the underlying microscopic traits of each potential. This approach offers a pathway to regulate optical absorption and refractive index outputs, particularly regarding resonance peak positions and amplitudes. Our calculations revealed that for small well widths, binding energy rises steeply with pressure, whereas at larger widths, the curves decrease gradually and slightly intersect. Fixing specific confinement parameters also proved effective in amplifying the binding energy. A wider quantum well corresponds to an extended radiative lifetime, and this temporal parameter is further suppressed under elevated hydrostatic pressure. Conversely, the oscillator strength demonstrates an inverse tendency, showing notable enhancement at higher pressure values, especially under Woods–Saxon confinement where its amplification is most significant. Absorption and refractive index spectra can be effectively modulated by hydrostatic pressure and confinement-defining parameters. Pöschl–Teller potential shows blue-shifted peaks with dimensional scaling, unlike Razavy and Woods–Saxon, which exhibit red shifts. All three potentials experience red shifts and intensity loss under elevated pressure. Photobleaching is least prominent in the Razavy case under tuned conditions, but more significant in the others at equal irradiance.
{"title":"Tunable quantum confinement under hydrostatic pressure: Exploring electronic and optical outputs in Pöschl–Teller, Razavy and Woods–Saxon potentials","authors":"M. Kavitha , A. Naifar , A. John Peter , V. Raja","doi":"10.1016/j.physe.2025.116339","DOIUrl":"10.1016/j.physe.2025.116339","url":null,"abstract":"<div><div>To bridge the gap identified in the current literature, this comprehensive and quantitative investigation examines the tunability of excitonic spectra and light–matter interaction characteristics under hydrostatic pressure, employing three distinct confinement models: Pöschl–Teller, Razavy and Woods–Saxon potentials. The analysis is carried out within the framework of the effective mass approximation, leveraging the density matrix approach to capture the nonlinear behaviour of the resulting optical coefficients. In addition, an in-depth assessment of the parameters influencing the spatial configuration of the confinement potentials was conducted to determine their impact on oscillator strength and radiative lifetime, thereby revealing the underlying microscopic traits of each potential. This approach offers a pathway to regulate optical absorption and refractive index outputs, particularly regarding resonance peak positions and amplitudes. Our calculations revealed that for small well widths, binding energy rises steeply with pressure, whereas at larger widths, the curves decrease gradually and slightly intersect. Fixing specific confinement parameters also proved effective in amplifying the binding energy. A wider quantum well corresponds to an extended radiative lifetime, and this temporal parameter is further suppressed under elevated hydrostatic pressure. Conversely, the oscillator strength demonstrates an inverse tendency, showing notable enhancement at higher pressure values, especially under Woods–Saxon confinement where its amplification is most significant. Absorption and refractive index spectra can be effectively modulated by hydrostatic pressure and confinement-defining parameters. Pöschl–Teller potential shows blue-shifted peaks with dimensional scaling, unlike Razavy and Woods–Saxon, which exhibit red shifts. All three potentials experience red shifts and intensity loss under elevated pressure. Photobleaching is least prominent in the Razavy case under tuned conditions, but more significant in the others at equal irradiance.</div></div>","PeriodicalId":20181,"journal":{"name":"Physica E-low-dimensional Systems & Nanostructures","volume":"174 ","pages":"Article 116339"},"PeriodicalIF":2.9,"publicationDate":"2025-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144771005","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 : 2025-10-01Epub Date: 2025-08-05DOI: 10.1016/j.physe.2025.116348
Sergo Rekhviashvili, Arsen Pskhu
We present an analytical investigation of an electron confined in a one-dimensional quantum well with a potential generated by two fixed positive charges at the boundaries. This system combines hard-wall confinement with long-range Coulomb interaction. By solving the stationary Schrödinger equation using convergent power series, we derive exact wavefunctions and energy levels. The energy spectrum contains both positive and negative values, depending on the well width. Notably, for a discrete set of well widths corresponding to triangular-number multiples of the Bohr radius, the ground state energy becomes exactly zero. These results provide a solvable model for confined Coulomb systems and offer insight into size quantization effects relevant to low-dimensional semiconductor structures, quantum dots, and high-pressure hydrides.
{"title":"One-dimensional quantum well with charges on the walls","authors":"Sergo Rekhviashvili, Arsen Pskhu","doi":"10.1016/j.physe.2025.116348","DOIUrl":"10.1016/j.physe.2025.116348","url":null,"abstract":"<div><div>We present an analytical investigation of an electron confined in a one-dimensional quantum well with a potential generated by two fixed positive charges at the boundaries. This system combines hard-wall confinement with long-range Coulomb interaction. By solving the stationary Schrödinger equation using convergent power series, we derive exact wavefunctions and energy levels. The energy spectrum contains both positive and negative values, depending on the well width. Notably, for a discrete set of well widths corresponding to triangular-number multiples of the Bohr radius, the ground state energy becomes exactly zero. These results provide a solvable model for confined Coulomb systems and offer insight into size quantization effects relevant to low-dimensional semiconductor structures, quantum dots, and high-pressure hydrides.</div></div>","PeriodicalId":20181,"journal":{"name":"Physica E-low-dimensional Systems & Nanostructures","volume":"174 ","pages":"Article 116348"},"PeriodicalIF":2.9,"publicationDate":"2025-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144781826","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 : 2025-10-01Epub Date: 2025-08-30DOI: 10.1016/j.physe.2025.116354
Rui Li (李睿)
The band inversion transition in a cylindrical HgTe nanowire is inducible via varying the nanowire radius. Here we derive the low-energy effective Hamiltonian describing the band structure of the HgTe nanowire close to the fundamental band gap. Because both the and subbands have quadratic dependence on when the gap closes, we need to consider at least three subbands, i.e., the , , and subbands, in building the effective Hamiltonian. The resulting effective Hamiltonian is block diagonal and each block is a 3 × 3 matrix. End states are found in the inverted regime when we solve the effective Hamiltonian with open boundary condition.
{"title":"Low-energy effective Hamiltonian and end states of an inverted HgTe nanowire","authors":"Rui Li (李睿)","doi":"10.1016/j.physe.2025.116354","DOIUrl":"10.1016/j.physe.2025.116354","url":null,"abstract":"<div><div>The band inversion transition in a cylindrical HgTe nanowire is inducible via varying the nanowire radius. Here we derive the low-energy effective Hamiltonian describing the band structure of the HgTe nanowire close to the fundamental band gap. Because both the <span><math><msub><mrow><mi>E</mi></mrow><mrow><mn>1</mn></mrow></msub></math></span> and <span><math><msub><mrow><mi>H</mi></mrow><mrow><mn>1</mn></mrow></msub></math></span> subbands have quadratic dependence on <span><math><msub><mrow><mi>k</mi></mrow><mrow><mi>z</mi></mrow></msub></math></span> when the gap closes, we need to consider at least three subbands, i.e., the <span><math><msub><mrow><mi>E</mi></mrow><mrow><mn>1</mn></mrow></msub></math></span>, <span><math><msub><mrow><mi>H</mi></mrow><mrow><mn>1</mn></mrow></msub></math></span>, and <span><math><msub><mrow><mi>H</mi></mrow><mrow><mn>2</mn></mrow></msub></math></span> subbands, in building the effective Hamiltonian. The resulting effective Hamiltonian is block diagonal and each block is a 3 × 3 matrix. End states are found in the inverted regime when we solve the effective Hamiltonian with open boundary condition.</div></div>","PeriodicalId":20181,"journal":{"name":"Physica E-low-dimensional Systems & Nanostructures","volume":"174 ","pages":"Article 116354"},"PeriodicalIF":2.9,"publicationDate":"2025-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144920368","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 : 2025-10-01Epub Date: 2025-08-31DOI: 10.1016/j.physe.2025.116359
Xin Han, Guoliang Wang, Zhaoyang Liu, Yanyan Yuan, Rui Lan
In this work, by modulating the stacking period of the individual GeTe and Sb2Te3 layers, a balance between electrical conductivity and Seebeck coefficient can be achieved to maximize the thermoelectric efficiency through the synergistic effect of material design flexibility and interface engineering. The coupling of acoustic and optical branches in the phonon dispersion of Sb2Te3, along with the presence of multi-carrier pockets in the band structure of GeTe, offers theoretical support for constructing a multilayer structure. The multilayer films sustain the two-phase structure composed of Sb2Te3 and GeTe phases. As the period number increases, there is an increase in optical band gap and carrier concentration, and a decrease in resistivity. The layered interface and nanocrystalline boundary inside the multilayer films are important scattering sources and significantly reduce the carrier mobility. In addition, nano-multilayer films modulate the carrier concentration to maintain an optimal order of 1019∼1020 cm−3. The maximum power factor of GeTe/Sb2Te3 multilayer films obtained is 1081 μW/mK2 at 473 K for single-period film. The power factor unexpectedly decreases as the number of periods in the film increases, which could be attributed to the enhanced thickness leading to higher carrier concentration and reduced nano scale effect.
{"title":"Enhanced thermoelectric properties in multilayer-modulated GeTe/Sb2Te3 films","authors":"Xin Han, Guoliang Wang, Zhaoyang Liu, Yanyan Yuan, Rui Lan","doi":"10.1016/j.physe.2025.116359","DOIUrl":"10.1016/j.physe.2025.116359","url":null,"abstract":"<div><div>In this work, by modulating the stacking period of the individual GeTe and Sb<sub>2</sub>Te<sub>3</sub> layers, a balance between electrical conductivity and Seebeck coefficient can be achieved to maximize the thermoelectric efficiency through the synergistic effect of material design flexibility and interface engineering. The coupling of acoustic and optical branches in the phonon dispersion of Sb<sub>2</sub>Te<sub>3</sub>, along with the presence of multi-carrier pockets in the band structure of GeTe, offers theoretical support for constructing a multilayer structure. The multilayer films sustain the two-phase structure composed of Sb<sub>2</sub>Te<sub>3</sub> and GeTe phases. As the period number increases, there is an increase in optical band gap and carrier concentration, and a decrease in resistivity. The layered interface and nanocrystalline boundary inside the multilayer films are important scattering sources and significantly reduce the carrier mobility. In addition, nano-multilayer films modulate the carrier concentration to maintain an optimal order of 10<sup>19</sup>∼10<sup>20</sup> cm<sup>−3</sup>. The maximum power factor of GeTe/Sb<sub>2</sub>Te<sub>3</sub> multilayer films obtained is 1081 μW/mK<sup>2</sup> at 473 K for single-period film. The power factor unexpectedly decreases as the number of periods in the film increases, which could be attributed to the enhanced thickness leading to higher carrier concentration and reduced nano scale effect.</div></div>","PeriodicalId":20181,"journal":{"name":"Physica E-low-dimensional Systems & Nanostructures","volume":"174 ","pages":"Article 116359"},"PeriodicalIF":2.9,"publicationDate":"2025-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144925296","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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