Pub 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":"2025-08-30","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 : 2025-08-30DOI: 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":"2025-08-30","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 : 2025-08-30DOI: 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":"2025-08-30","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 : 2025-08-14DOI: 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":"2025-08-14","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 : 2025-08-09DOI: 10.1016/j.physe.2025.116351
M.P. Telenkov, Yu.A. Mityagin, D.S. Korchagin
Electron scattering with longitudinal polar optical phonons in a quantizing magnetic field tilted to the plane of quantum well layers is studied. The expressions are derived for the electron scattering rate due to longitudinal polar optical phonon emission in a tilted quantizing magnetic field. The effect of variations in both the magnitude and orientation of the magnetic field on the electron-phonon scattering processes is studied. The different relation between the inter-subband spacing and the optical phonon energy are considered – when the inter-subband spacing is greater than, equal to, and lower than the optical phonon energy. Principal transformation of the inter-subband scattering rate dependence on the quantizing component of the magnetic field – from oscillatory to monotonic – was found to occur when inter-subband spacing comes closer to optical phonon frequency.
{"title":"Electron-optical phonon scattering in quantum wells in a tilted quantizing magnetic field","authors":"M.P. Telenkov, Yu.A. Mityagin, D.S. Korchagin","doi":"10.1016/j.physe.2025.116351","DOIUrl":"10.1016/j.physe.2025.116351","url":null,"abstract":"<div><div>Electron scattering with longitudinal polar optical phonons in a quantizing magnetic field tilted to the plane of quantum well layers is studied. The expressions are derived for the electron scattering rate due to longitudinal polar optical phonon emission in a tilted quantizing magnetic field. The effect of variations in both the magnitude and orientation of the magnetic field on the electron-phonon scattering processes is studied. The different relation between the inter-subband spacing and the optical phonon energy are considered – when the inter-subband spacing is greater than, equal to, and lower than the optical phonon energy. Principal transformation of the inter-subband scattering rate dependence on the quantizing component of the magnetic field – from oscillatory to monotonic – was found to occur when inter-subband spacing comes closer to optical phonon frequency.</div></div>","PeriodicalId":20181,"journal":{"name":"Physica E-low-dimensional Systems & Nanostructures","volume":"174 ","pages":"Article 116351"},"PeriodicalIF":2.9,"publicationDate":"2025-08-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144878252","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 : 2025-08-09DOI: 10.1016/j.physe.2025.116350
Hayet Saghrouni , Lotfi Beji
In this study, dysprosium oxide thin films with a thickness of 15 nm were deposited onto an n-type gallium arsenide (111) substrate using electron beam evaporation under ultra-high vacuum conditions. The deposition process, carried out at 250 °C and followed by thermal annealing at 400 °C, yielded uniformly smooth films with good structural quality and interfacial integrity. Structural analysis through scanning electron microscopy and X-ray diffraction revealed uniform triangular surface features and confirmed the cubic phase of dysprosium oxide, with crystallographic alignment to the gallium arsenide substrate. Fourier-transform infrared spectroscopy validated the formation of dysprosium–oxygen bonds. The optical properties were extracted using spectroscopic ellipsometry. The refractive index exhibited normal dispersion, and the optical band gap was determined to be 4.09 ± 0.03 eV. Wemple–DiDomenico modeling provided the oscillator energy (5.02 ± 0.05 eV) and dispersion energy (9.80 ± 0.07 eV), while dielectric function analysis identified sharp electronic transitions attributed to intra-4f states of trivalent dysprosium ions. In the infrared region, classical dispersion relations enabled the extraction of key parameters, including the high-frequency dielectric constant (3.28 ± 0.05), plasma frequency (1.81 ± 0.04) × 1014 Hz, carrier relaxation time (2.26 ± 0.03) × 10−15 s, and carrier concentration to effective mass ratio ((3.69 ± 0.08) × 1047 g−1 cm−3). Energy loss analysis through surface and volume energy loss functions revealed distinct plasmonic and interband excitation features. Optical conductivity measurements highlighted excitonic and bulk plasmon activity in the 2.7–3.8 eV range. Nonlinear optical behavior was evaluated using Miller's rule, yielding a linear susceptibility of 0.155 ± 0.004 esu, a third-order susceptibility of (9.74 ± 0.21) × 10−14 esu, and a nonlinear refractive index of (2.40 ± 0.06) × 10−12 esu. Overall, the dysprosium oxide thin films demonstrated excellent crystallinity, high optical quality, and strong third-order nonlinear response, positioning them as promising candidates for advanced optoelectronic and photonic applications, including ultraviolet photodetectors, nonlinear optical modulators, and integrated optical devices.
{"title":"Structural and optical characterization of electron Beam–Deposited Dy2O3 thin films on n-GaAs(111) substrate for photonic applications","authors":"Hayet Saghrouni , Lotfi Beji","doi":"10.1016/j.physe.2025.116350","DOIUrl":"10.1016/j.physe.2025.116350","url":null,"abstract":"<div><div>In this study, dysprosium oxide thin films with a thickness of 15 nm were deposited onto an n-type gallium arsenide (111) substrate using electron beam evaporation under ultra-high vacuum conditions. The deposition process, carried out at 250 °C and followed by thermal annealing at 400 °C, yielded uniformly smooth films with good structural quality and interfacial integrity. Structural analysis through scanning electron microscopy and X-ray diffraction revealed uniform triangular surface features and confirmed the cubic phase of dysprosium oxide, with crystallographic alignment to the gallium arsenide substrate. Fourier-transform infrared spectroscopy validated the formation of dysprosium–oxygen bonds. The optical properties were extracted using spectroscopic ellipsometry. The refractive index exhibited normal dispersion, and the optical band gap was determined to be 4.09 ± 0.03 eV. Wemple–DiDomenico modeling provided the oscillator energy (5.02 ± 0.05 eV) and dispersion energy (9.80 ± 0.07 eV), while dielectric function analysis identified sharp electronic transitions attributed to intra-4f states of trivalent dysprosium ions. In the infrared region, classical dispersion relations enabled the extraction of key parameters, including the high-frequency dielectric constant (3.28 ± 0.05), plasma frequency (1.81 ± 0.04) × 10<sup>14</sup> Hz, carrier relaxation time (2.26 ± 0.03) × 10<sup>−15</sup> s, and carrier concentration to effective mass ratio ((3.69 ± 0.08) × 10<sup>47</sup> g<sup>−1</sup> cm<sup>−3</sup>). Energy loss analysis through surface and volume energy loss functions revealed distinct plasmonic and interband excitation features. Optical conductivity measurements highlighted excitonic and bulk plasmon activity in the 2.7–3.8 eV range. Nonlinear optical behavior was evaluated using Miller's rule, yielding a linear susceptibility of 0.155 ± 0.004 esu, a third-order susceptibility of (9.74 ± 0.21) × 10<sup>−14</sup> esu, and a nonlinear refractive index of (2.40 ± 0.06) × 10<sup>−12</sup> esu. Overall, the dysprosium oxide thin films demonstrated excellent crystallinity, high optical quality, and strong third-order nonlinear response, positioning them as promising candidates for advanced optoelectronic and photonic applications, including ultraviolet photodetectors, nonlinear optical modulators, and integrated optical devices.</div></div>","PeriodicalId":20181,"journal":{"name":"Physica E-low-dimensional Systems & Nanostructures","volume":"174 ","pages":"Article 116350"},"PeriodicalIF":2.9,"publicationDate":"2025-08-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144810454","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 : 2025-08-06DOI: 10.1016/j.physe.2025.116349
Er'el Granot
This paper investigates the emergence of classical-like behavior within a fundamentally quantum system. Our findings demonstrate that even when quantum phenomena, such as tunneling, are dominant, their collective behavior can yield a macroscopic observable -specifically conductance-that is quantitatively described by classical parameters, notably without the explicit appearance of Planck's constant, h. We show that this "classical-like" domain is not a parameter-specific coincidence but a robust feature that exists near a specific point. Our analysis reveals a striking insensitivity to the precise value of h; quantitatively, a relative change in conductance ΔG/G is found to be less than (Δh/h)2, implying a suppressed dependence on h beyond simple linear scaling. This finding challenges conventional paradigms of the quantum-to-classical transition, which typically invoke the limit where h→0, by proposing an alternative mechanism for classical emergence rooted in the collective behavior of quantum effects. Intriguingly, these results predict that the conductance within this "classical-like" regime is consistently approximately 0.75G0 (where G0 = 2e2/h), a value that arises when the specific conditions for the emergence of this regime are met. The close proximity of this theoretical value to the long-standing 0.7G0 anomaly observed in quantum point contacts hints at a potential intrinsic connection. Investigating this relationship may offer new avenues for understanding the origins of this puzzle and providing deeper insights into the complex interplay between quantum coherence, interactions, and classical phenomenology in mesoscopic systems.
{"title":"Emergence of classical-like conductance extremum in a quantum wire with a narrow barrier","authors":"Er'el Granot","doi":"10.1016/j.physe.2025.116349","DOIUrl":"10.1016/j.physe.2025.116349","url":null,"abstract":"<div><div>This paper investigates the emergence of classical-like behavior within a fundamentally quantum system. Our findings demonstrate that even when quantum phenomena, such as tunneling, are dominant, their collective behavior can yield a macroscopic observable -specifically conductance-that is quantitatively described by classical parameters, notably without the explicit appearance of Planck's constant, <em>h</em>. We show that this \"classical-like\" domain is not a parameter-specific coincidence but a robust feature that exists near a specific point. Our analysis reveals a striking insensitivity to the precise value of <em>h</em>; quantitatively, a relative change in conductance Δ<em>G</em>/<em>G</em> is found to be less than (Δ<em>h</em>/<em>h</em>)<sup>2</sup>, implying a suppressed dependence on <em>h</em> beyond simple linear scaling. This finding challenges conventional paradigms of the quantum-to-classical transition, which typically invoke the limit where <em>h</em>→0, by proposing an alternative mechanism for classical emergence rooted in the collective behavior of quantum effects. Intriguingly, these results predict that the conductance within this \"classical-like\" regime is consistently approximately 0.75<em>G</em><sub>0</sub> (where <em>G</em><sub>0</sub> = 2e<sup>2</sup>/<em>h</em>), a value that arises when the specific conditions for the emergence of this regime are met. The close proximity of this theoretical value to the long-standing 0.7<em>G</em><sub>0</sub> anomaly observed in quantum point contacts hints at a potential intrinsic connection. Investigating this relationship may offer new avenues for understanding the origins of this puzzle and providing deeper insights into the complex interplay between quantum coherence, interactions, and classical phenomenology in mesoscopic systems.</div></div>","PeriodicalId":20181,"journal":{"name":"Physica E-low-dimensional Systems & Nanostructures","volume":"174 ","pages":"Article 116349"},"PeriodicalIF":2.9,"publicationDate":"2025-08-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144809694","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 : 2025-08-05DOI: 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":"2025-08-05","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 : 2025-07-30DOI: 10.1016/j.physe.2025.116333
Shiming Zheng, E.S. Khramtsov, I.V. Ignatiev
A microscopic model of a heterostructure with a quantum well (QW) is proposed to study exciton properties in an external electric field. The effect of an electric field ranging from 0 to 6 kV/cm applied to a GaAs/AlGaAs QW structure in the growth direction is studied for several QWs of various widths up to 100 nm. The three-dimensional Schrödinger equation (SE) for the exciton is numerically solved using the finite difference method. Wave functions and energies of several states of the heavy-hole and light-hole excitons are calculated. The dependencies of exciton state energy, binding energy, radiative broadening, and static dipole moment on the applied electric field are determined. Additionally, the threshold for exciton dissociation in the 100-nm QW is established. Furthermore, we calculate an electric-field-induced shift in the center of mass of heavy-hole and light-hole excitons in the QWs. Finally, we simulate the reflection spectra of heterostructures with GaAs/AlGaAs QWs under an electric field using the calculated energies, radiative broadenings, and phases of exciton resonances.
{"title":"Effect of electric field on excitons in wide quantum wells","authors":"Shiming Zheng, E.S. Khramtsov, I.V. Ignatiev","doi":"10.1016/j.physe.2025.116333","DOIUrl":"10.1016/j.physe.2025.116333","url":null,"abstract":"<div><div>A microscopic model of a heterostructure with a quantum well (QW) is proposed to study exciton properties in an external electric field. The effect of an electric field ranging from 0 to 6 kV/cm applied to a GaAs/AlGaAs QW structure in the growth direction is studied for several QWs of various widths up to 100 nm. The three-dimensional Schrödinger equation (SE) for the exciton is numerically solved using the finite difference method. Wave functions and energies of several states of the heavy-hole and light-hole excitons are calculated. The dependencies of exciton state energy, binding energy, radiative broadening, and static dipole moment on the applied electric field are determined. Additionally, the threshold for exciton dissociation in the 100-nm QW is established. Furthermore, we calculate an electric-field-induced shift in the center of mass of heavy-hole and light-hole excitons in the QWs. Finally, we simulate the reflection spectra of heterostructures with GaAs/AlGaAs QWs under an electric field using the calculated energies, radiative broadenings, and phases of exciton resonances.</div></div>","PeriodicalId":20181,"journal":{"name":"Physica E-low-dimensional Systems & Nanostructures","volume":"174 ","pages":"Article 116333"},"PeriodicalIF":2.9,"publicationDate":"2025-07-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144781827","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 : 2025-07-30DOI: 10.1016/j.physe.2025.116340
Leonardo Carneiro Quaresma , Jonas Marinho Duarte , Denner Felipe Silva Ferreira , Carlos Alberto Brito da Silva Jr. , Jordan Del Nero
We report a comprehensive theoretical investigation of the two-dimensional carbon allotrope C-57, comprised of fused pentagonal and heptagonal rings, focusing on its electronic structure and transport properties. Using density functional theory (DFT) with SIESTA and non-equilibrium Green's function (NEGF) transport simulations via TranSIESTA, we demonstrate that pristine C-57 is intrinsically metallic, with multiple bands crossing the Fermi level and room-temperature carrier mobilities of 103–104 cm2V−1s−1. Edge hydrogenation opens a direct band gap of 0.437 eV, yielding semiconducting nanoribbons that exhibit negligible current below |V| ≃ 0.45 V and a sharp turn-on above threshold. Two- and three-dimensional maps of the density of states and transmission coefficients elucidate bias-tunable resonances governing conductance modulation. Comparison with other 2D carbon allotropes – such as graphdiyne and penta-graphene – highlights C-57's intermediate gap and reversible metal-to-semiconductor transition via chemical functionalization. These features position C-57 as a versatile all-carbon platform for low-voltage field-effect transistors, reconfigurable logic elements, and nanoscale sensors.
{"title":"Electronic transport modulation in C-57: A path toward carbon-based logic and switching devices","authors":"Leonardo Carneiro Quaresma , Jonas Marinho Duarte , Denner Felipe Silva Ferreira , Carlos Alberto Brito da Silva Jr. , Jordan Del Nero","doi":"10.1016/j.physe.2025.116340","DOIUrl":"10.1016/j.physe.2025.116340","url":null,"abstract":"<div><div>We report a comprehensive theoretical investigation of the two-dimensional carbon allotrope C-57, comprised of fused pentagonal and heptagonal rings, focusing on its electronic structure and transport properties. Using density functional theory (DFT) with SIESTA and non-equilibrium Green's function (NEGF) transport simulations via TranSIESTA, we demonstrate that pristine C-57 is intrinsically metallic, with multiple bands crossing the Fermi level and room-temperature carrier mobilities of 10<sup>3</sup>–10<sup>4</sup> cm<sup>2</sup>V<sup>−1</sup>s<sup>−1</sup>. Edge hydrogenation opens a direct band gap of 0.437 eV, yielding semiconducting nanoribbons that exhibit negligible current below |V| ≃ 0.45 V and a sharp turn-on above threshold. Two- and three-dimensional maps of the density of states and transmission coefficients elucidate bias-tunable resonances governing conductance modulation. Comparison with other 2D carbon allotropes – such as graphdiyne and penta-graphene – highlights C-57's intermediate gap and reversible metal-to-semiconductor transition via chemical functionalization. These features position C-57 as a versatile all-carbon platform for low-voltage field-effect transistors, reconfigurable logic elements, and nanoscale sensors.</div></div>","PeriodicalId":20181,"journal":{"name":"Physica E-low-dimensional Systems & Nanostructures","volume":"174 ","pages":"Article 116340"},"PeriodicalIF":2.9,"publicationDate":"2025-07-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144771004","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}
扫码关注我们
求助内容：
应助结果提醒方式：
京公网安备 11010802042870号