Pub Date : 2025-10-08DOI: 10.1016/j.physe.2025.116383
Raymond J. Hartig , Ioan Grosu , Ionel Ţifrea
<div><div>We investigate the nonlinear thermoelectric transport in a generic nanoscale device connected to two side reservoirs at different temperatures (<span><math><msub><mrow><mi>T</mi></mrow><mrow><mi>L</mi></mrow></msub></math></span> and <span><math><msub><mrow><mi>T</mi></mrow><mrow><mi>R</mi></mrow></msub></math></span>) and chemical potentials (<span><math><msub><mrow><mi>μ</mi></mrow><mrow><mi>L</mi></mrow></msub></math></span> and <span><math><msub><mrow><mi>μ</mi></mrow><mrow><mi>R</mi></mrow></msub></math></span>). We derive equations for the charge (electric) and heat (thermal) currents. These equations allow for the estimation of the second order contributions to the system’s thermoelectric response and the <em>analytical</em> derivation of the first nonlinear contributions to the system’s electric conductance <span><math><msup><mrow><mi>σ</mi></mrow><mrow><mrow><mo>(</mo><mn>2</mn><mo>)</mo></mrow></mrow></msup></math></span>, Seebeck coefficient <span><math><msup><mrow><mi>S</mi></mrow><mrow><mrow><mo>(</mo><mn>2</mn><mo>)</mo></mrow></mrow></msup></math></span>, and electronic thermal conductance <span><math><msubsup><mrow><mi>κ</mi></mrow><mrow><mi>e</mi><mi>l</mi></mrow><mrow><mrow><mo>(</mo><mn>2</mn><mo>)</mo></mrow></mrow></msubsup></math></span>. In the generation mode, when the system’s output power is positive (<span><math><mrow><mi>P</mi><mo>></mo><mn>0</mn></mrow></math></span>), we estimate the maximum output power and efficiency of the system. The results are general and rely on generic dimensionless kinetic transport coefficients <span><math><mrow><msubsup><mrow><mi>K</mi></mrow><mrow><mi>n</mi></mrow><mrow><mi>p</mi></mrow></msubsup><mrow><mo>(</mo><mi>μ</mi><mo>,</mo><mi>T</mi><mo>)</mo></mrow></mrow></math></span> that depends on the system’s characteristic electronic transmission function <span><math><mrow><mi>τ</mi><mrow><mo>(</mo><mi>E</mi><mo>)</mo></mrow></mrow></math></span>. To outline the differences between the linear and nonlinear approximations we consider the particular case of a generalized Fano line-shape electronic transmission function and exactly calculate the dimensionless kinetic transport coefficients in terms of Hurwitz zeta functions and Bernoulli numbers. The output power efficiency of the system is estimated as function of the energy <span><math><mrow><mi>ɛ</mi><mo>=</mo><mrow><mo>(</mo><msub><mrow><mi>E</mi></mrow><mrow><mi>d</mi></mrow></msub><mo>−</mo><mi>μ</mi><mo>)</mo></mrow><mo>/</mo><msub><mrow><mi>k</mi></mrow><mrow><mi>B</mi></mrow></msub><mi>T</mi></mrow></math></span> and broadening <span><math><mrow><mi>γ</mi><mo>=</mo><msub><mrow><mi>Γ</mi></mrow><mrow><mi>d</mi></mrow></msub><mo>/</mo><msub><mrow><mi>k</mi></mrow><mrow><mi>B</mi></mrow></msub><mi>T</mi></mrow></math></span> parameters. These results support the need for higher order terms in the theoretical analysis of the thermoelectric transport in nanoscale devices and allow for the optimization of the system’s propert
{"title":"Nonlinear corrections to the thermoelectric efficiency of a nanoscale device","authors":"Raymond J. Hartig , Ioan Grosu , Ionel Ţifrea","doi":"10.1016/j.physe.2025.116383","DOIUrl":"10.1016/j.physe.2025.116383","url":null,"abstract":"<div><div>We investigate the nonlinear thermoelectric transport in a generic nanoscale device connected to two side reservoirs at different temperatures (<span><math><msub><mrow><mi>T</mi></mrow><mrow><mi>L</mi></mrow></msub></math></span> and <span><math><msub><mrow><mi>T</mi></mrow><mrow><mi>R</mi></mrow></msub></math></span>) and chemical potentials (<span><math><msub><mrow><mi>μ</mi></mrow><mrow><mi>L</mi></mrow></msub></math></span> and <span><math><msub><mrow><mi>μ</mi></mrow><mrow><mi>R</mi></mrow></msub></math></span>). We derive equations for the charge (electric) and heat (thermal) currents. These equations allow for the estimation of the second order contributions to the system’s thermoelectric response and the <em>analytical</em> derivation of the first nonlinear contributions to the system’s electric conductance <span><math><msup><mrow><mi>σ</mi></mrow><mrow><mrow><mo>(</mo><mn>2</mn><mo>)</mo></mrow></mrow></msup></math></span>, Seebeck coefficient <span><math><msup><mrow><mi>S</mi></mrow><mrow><mrow><mo>(</mo><mn>2</mn><mo>)</mo></mrow></mrow></msup></math></span>, and electronic thermal conductance <span><math><msubsup><mrow><mi>κ</mi></mrow><mrow><mi>e</mi><mi>l</mi></mrow><mrow><mrow><mo>(</mo><mn>2</mn><mo>)</mo></mrow></mrow></msubsup></math></span>. In the generation mode, when the system’s output power is positive (<span><math><mrow><mi>P</mi><mo>></mo><mn>0</mn></mrow></math></span>), we estimate the maximum output power and efficiency of the system. The results are general and rely on generic dimensionless kinetic transport coefficients <span><math><mrow><msubsup><mrow><mi>K</mi></mrow><mrow><mi>n</mi></mrow><mrow><mi>p</mi></mrow></msubsup><mrow><mo>(</mo><mi>μ</mi><mo>,</mo><mi>T</mi><mo>)</mo></mrow></mrow></math></span> that depends on the system’s characteristic electronic transmission function <span><math><mrow><mi>τ</mi><mrow><mo>(</mo><mi>E</mi><mo>)</mo></mrow></mrow></math></span>. To outline the differences between the linear and nonlinear approximations we consider the particular case of a generalized Fano line-shape electronic transmission function and exactly calculate the dimensionless kinetic transport coefficients in terms of Hurwitz zeta functions and Bernoulli numbers. The output power efficiency of the system is estimated as function of the energy <span><math><mrow><mi>ɛ</mi><mo>=</mo><mrow><mo>(</mo><msub><mrow><mi>E</mi></mrow><mrow><mi>d</mi></mrow></msub><mo>−</mo><mi>μ</mi><mo>)</mo></mrow><mo>/</mo><msub><mrow><mi>k</mi></mrow><mrow><mi>B</mi></mrow></msub><mi>T</mi></mrow></math></span> and broadening <span><math><mrow><mi>γ</mi><mo>=</mo><msub><mrow><mi>Γ</mi></mrow><mrow><mi>d</mi></mrow></msub><mo>/</mo><msub><mrow><mi>k</mi></mrow><mrow><mi>B</mi></mrow></msub><mi>T</mi></mrow></math></span> parameters. These results support the need for higher order terms in the theoretical analysis of the thermoelectric transport in nanoscale devices and allow for the optimization of the system’s propert","PeriodicalId":20181,"journal":{"name":"Physica E-low-dimensional Systems & Nanostructures","volume":"175 ","pages":"Article 116383"},"PeriodicalIF":2.9,"publicationDate":"2025-10-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145267668","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 : 2025-10-08DOI: 10.1016/j.physe.2025.116386
F. Castañeda-Ramírez , M. Martínez-Mares , A.M. Martínez-Argüello
The statistical fluctuations of the voltage across a quantum wire in a four-terminal arrangement, where two of the terminals are used as probes while the other two are used to establish a flux current, is studied in the single channel case. The quantum wire to be measured consists of a chaotic microcavity or a disordered conductor in the presence of one of the three symmetry classes: orthogonal, unitary, or symplectic. Using the circular ensembles of random matrix theory or the Dorokov–Mello–Pereyra–Kumar (DMPK) equation, the statistical distribution of the voltage is reduced to quadratures for noninvasive probes which is solved numerically. Numerical simulations from random matrix theory or for the DMPK equation are performed for any coupling strength of the probes. For the chaotic cavity the effect of the symmetry class is clearly manifested through the weak and weak anti-localization phenomena for the orthogonal and symplectic symmetry classes, respectively. A similar effect is found, but with respect to the degree of disorder in a quantum wire as it evolves from strong to weak disorder: a simple correspondence between the label of the symmetry class and the degree of disorder, is found.
{"title":"Voltage fluctuations in a four-terminal quantum device with orthogonal, unitary or symplectic symmetry","authors":"F. Castañeda-Ramírez , M. Martínez-Mares , A.M. Martínez-Argüello","doi":"10.1016/j.physe.2025.116386","DOIUrl":"10.1016/j.physe.2025.116386","url":null,"abstract":"<div><div>The statistical fluctuations of the voltage across a quantum wire in a four-terminal arrangement, where two of the terminals are used as probes while the other two are used to establish a flux current, is studied in the single channel case. The quantum wire to be measured consists of a chaotic microcavity or a disordered conductor in the presence of one of the three symmetry classes: orthogonal, unitary, or symplectic. Using the circular ensembles of random matrix theory or the Dorokov–Mello–Pereyra–Kumar (DMPK) equation, the statistical distribution of the voltage is reduced to quadratures for noninvasive probes which is solved numerically. Numerical simulations from random matrix theory or for the DMPK equation are performed for any coupling strength of the probes. For the chaotic cavity the effect of the symmetry class is clearly manifested through the weak and weak anti-localization phenomena for the orthogonal and symplectic symmetry classes, respectively. A similar effect is found, but with respect to the degree of disorder in a quantum wire as it evolves from strong to weak disorder: a simple correspondence between the label of the symmetry class and the degree of disorder, is found.</div></div>","PeriodicalId":20181,"journal":{"name":"Physica E-low-dimensional Systems & Nanostructures","volume":"175 ","pages":"Article 116386"},"PeriodicalIF":2.9,"publicationDate":"2025-10-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145267671","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 : 2025-09-30DOI: 10.1016/j.physe.2025.116381
Carlos Magno O. Pereira, Edilberto O. Silva
We predict a new class of quantum Hall phenomena in completely neutral systems, demonstrating that the interplay between radial electric fields and dipole moments induces exact quantization without Landau levels or external magnetic fields. Contrary to conventional wisdom, our theory reveals that: (i) the singularity of line charges does not destroy topological protection, (ii) spin control of quantization emerges from boundary conditions alone, and (iii) the effect persists up to 25 K, surpassing typical neutral systems. These findings establish electric field engineering as a viable route to topological matter beyond magnetic paradigms.
{"title":"Quantum Hall-like effect for neutral particles with magnetic dipole moments in a quantum dot","authors":"Carlos Magno O. Pereira, Edilberto O. Silva","doi":"10.1016/j.physe.2025.116381","DOIUrl":"10.1016/j.physe.2025.116381","url":null,"abstract":"<div><div>We predict a new class of quantum Hall phenomena in completely neutral systems, demonstrating that the interplay between radial electric fields and dipole moments induces exact <span><math><mrow><msup><mrow><mi>e</mi></mrow><mrow><mn>2</mn></mrow></msup><mo>/</mo><mi>h</mi></mrow></math></span> quantization without Landau levels or external magnetic fields. Contrary to conventional wisdom, our theory reveals that: (i) the singularity of line charges does not destroy topological protection, (ii) spin control of quantization emerges from boundary conditions alone, and (iii) the effect persists up to 25 K, surpassing typical neutral systems. These findings establish electric field engineering as a viable route to topological matter beyond magnetic paradigms.</div></div>","PeriodicalId":20181,"journal":{"name":"Physica E-low-dimensional Systems & Nanostructures","volume":"175 ","pages":"Article 116381"},"PeriodicalIF":2.9,"publicationDate":"2025-09-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145220919","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 : 2025-09-30DOI: 10.1016/j.physe.2025.116384
Khatir Ouail, Samia Ferahtia, Salima Saib, Nadir Bouarissa
Through comprehensive first-principles calculations coupled with Boltzmann transport theory, we systematically investigate the strain-dependent structural, mechanical, electronic, and thermoelectric properties of monolayer ZrX2 (X = S, Se). Our mechanical analysis reveals both materials maintain exceptional stability under biaxial strains ranging from −10 % to +10 %, with ZrS2 exhibiting superior mechanical robustness as evidenced by its higher Young's modulus (73.95 N/m) compared to ZrSe2 (63.70 N/m). Detailed electronic structure calculations employing the TB-mBJ potential demonstrate these monolayers are indirect band gap semiconductors, with fundamental gaps of 1.8 eV for ZrS2 and 1.16 eV for ZrSe2. Notably, compressive strain induces dramatic electronic transitions, reducing the band gap progressively until ZrSe2 undergoes a complete semiconductor-to-metal transition at −10 % strain. The thermoelectric transport properties show remarkable strain sensitivity. Applied biaxial strain enhances the power factor by an order of magnitude, reaching exceptional values of 2.4 × 1011 W/mK2s for ZrSe2 at −6 % strain. Comparative analysis reveals n-type doping consistently outperforms p-type configurations in thermoelectric efficiency across all strain conditions. These enhancements originate from strain-induced modifications to both electronic band structures and carrier scattering mechanisms. Our combined mechanical, electronic, and thermoelectric characterization provides fundamental insights into the strain-response of ZrX2 monolayers, demonstrating their exceptional tunability for next-generation flexible electronics, strain sensors, and high-efficiency energy conversion devices. The comprehensive dataset presented here establishes a foundation for future experimental investigations and device applications of these promising 2D materials.
{"title":"Strain-engineered electronic and thermoelectric properties of ZrX2 (X=S, Se) monolayers: A first-principles study","authors":"Khatir Ouail, Samia Ferahtia, Salima Saib, Nadir Bouarissa","doi":"10.1016/j.physe.2025.116384","DOIUrl":"10.1016/j.physe.2025.116384","url":null,"abstract":"<div><div>Through comprehensive first-principles calculations coupled with Boltzmann transport theory, we systematically investigate the strain-dependent structural, mechanical, electronic, and thermoelectric properties of monolayer ZrX<sub>2</sub> (X = S, Se). Our mechanical analysis reveals both materials maintain exceptional stability under biaxial strains ranging from −10 % to +10 %, with ZrS<sub>2</sub> exhibiting superior mechanical robustness as evidenced by its higher Young's modulus (73.95 N/m) compared to ZrSe<sub>2</sub> (63.70 N/m). Detailed electronic structure calculations employing the TB-mBJ potential demonstrate these monolayers are indirect band gap semiconductors, with fundamental gaps of 1.8 eV for ZrS<sub>2</sub> and 1.16 eV for ZrSe<sub>2</sub>. Notably, compressive strain induces dramatic electronic transitions, reducing the band gap progressively until ZrSe<sub>2</sub> undergoes a complete semiconductor-to-metal transition at −10 % strain. The thermoelectric transport properties show remarkable strain sensitivity. Applied biaxial strain enhances the power factor by an order of magnitude, reaching exceptional values of 2.4 × 10<sup>11</sup> W/mK<sup>2</sup>s for ZrSe<sub>2</sub> at −6 % strain. Comparative analysis reveals n-type doping consistently outperforms p-type configurations in thermoelectric efficiency across all strain conditions. These enhancements originate from strain-induced modifications to both electronic band structures and carrier scattering mechanisms. Our combined mechanical, electronic, and thermoelectric characterization provides fundamental insights into the strain-response of ZrX<sub>2</sub> monolayers, demonstrating their exceptional tunability for next-generation flexible electronics, strain sensors, and high-efficiency energy conversion devices. The comprehensive dataset presented here establishes a foundation for future experimental investigations and device applications of these promising 2D materials.</div></div>","PeriodicalId":20181,"journal":{"name":"Physica E-low-dimensional Systems & Nanostructures","volume":"175 ","pages":"Article 116384"},"PeriodicalIF":2.9,"publicationDate":"2025-09-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145267672","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 : 2025-09-29DOI: 10.1016/j.physe.2025.116382
Limei Zheng, Yu Li, Dazhi Sun, Baozeng Zhou, Xiaocha Wang
Two-dimensional (2D) transition-metal trihalides have received extensive attention in the field of novel spintronic devices and heterostructure coupling is an effective method for achieving multifunctional integration and regulation. In this work, using first-principles calculations, we systematically study the electronic structure and magnetic properties of the 2D MnF3/graphene heterostructures. MnF3 monolayer exhibits Dirac half-metal properties, with electron states featuring Dirac cones in its single spin channel. With different stacking configurations, the electronic properties of both are well preserved from the band structure, interfacial charge transfer only causes the relative movement of the electronic states. Additionally, due to the broken sublattice symmetry of MnF3 in heterostructure, a gap opening of 24.9 meV appears around the spin-polarized Dirac cone in MnF3. Moreover, the formation of heterostructure significantly enhances the in-plane magnetic anisotropy of the MnF3 monolayer. By reducing the interlayer distance, the spin-polarized Dirac cone has a larger gap opening of 555.5 meV, which induces the transition of MnF3 from Dirac half-metal to magnetic semiconductor, and the Curie temperature (TC) increases obviously. Furthermore, a spin logic device based on MnF3/graphene heterostructures is proposed, which can complete the resistive state switching from the "1″ state to the "0″ state by application of pressure. These results provide a reference for the application of MnF3/graphene heterostructure in spintronic devices.
{"title":"Broken sublattice symmetry induced gap opening of spin-polarized Dirac cone in MnF3","authors":"Limei Zheng, Yu Li, Dazhi Sun, Baozeng Zhou, Xiaocha Wang","doi":"10.1016/j.physe.2025.116382","DOIUrl":"10.1016/j.physe.2025.116382","url":null,"abstract":"<div><div>Two-dimensional (2D) transition-metal trihalides have received extensive attention in the field of novel spintronic devices and heterostructure coupling is an effective method for achieving multifunctional integration and regulation. In this work, using first-principles calculations, we systematically study the electronic structure and magnetic properties of the 2D MnF<sub>3</sub>/graphene heterostructures. MnF<sub>3</sub> monolayer exhibits Dirac half-metal properties, with electron states featuring Dirac cones in its single spin channel. With different stacking configurations, the electronic properties of both are well preserved from the band structure, interfacial charge transfer only causes the relative movement of the electronic states. Additionally, due to the broken sublattice symmetry of MnF<sub>3</sub> in heterostructure, a gap opening of 24.9 meV appears around the spin-polarized Dirac cone in MnF<sub>3</sub>. Moreover, the formation of heterostructure significantly enhances the in-plane magnetic anisotropy of the MnF<sub>3</sub> monolayer. By reducing the interlayer distance, the spin-polarized Dirac cone has a larger gap opening of 555.5 meV, which induces the transition of MnF<sub>3</sub> from Dirac half-metal to magnetic semiconductor, and the Curie temperature (<em>T</em><sub>C</sub>) increases obviously. Furthermore, a spin logic device based on MnF<sub>3</sub>/graphene heterostructures is proposed, which can complete the resistive state switching from the \"1″ state to the \"0″ state by application of pressure. These results provide a reference for the application of MnF<sub>3</sub>/graphene heterostructure in spintronic devices.</div></div>","PeriodicalId":20181,"journal":{"name":"Physica E-low-dimensional Systems & Nanostructures","volume":"175 ","pages":"Article 116382"},"PeriodicalIF":2.9,"publicationDate":"2025-09-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145220920","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 : 2025-09-25DOI: 10.1016/j.physe.2025.116378
K.V. Jayaprasad, Titu Thomas, Manu Vaishakh, Sheenu Thomas
The growing demand for efficient nonlinear optical (NLO) materials for photonic devices such as isolators, switches, and telecommunication components necessitates the exploration of new nanostructured systems. Transition metal oxides like Mn3O4, with strong electronic interactions and thermal responses, remain relatively underexplored for their NLO behavior. In this work, Mn3O4 nanoparticles synthesized via ultrasonication-assisted precipitation were investigated using spatial self-phase modulation (SSPM) with a 532 nm CW DPSS laser. Structural and morphological characteristics were confirmed by XRD and TEM analyses. Nonlinear optical parameters, including the nonlinear refractive index (n2) and thermo-optic coefficient , were determined from the variation of SSPM patterns with laser intensity. Furthermore, a photonic diode based on a cascaded Mn3O4/TiO2 hybrid structure was demonstrated, enabling nonreciprocal light propagation through unidirectional SSPM excitation. These findings highlight Mn3O4 nanoparticles as promising candidates for NLO applications, while the proposed hybrid photonic diode offers potential in integrated optics, optical switching, and telecommunication technologies.
{"title":"Optical photonic diode realization through spatial self-phase modulation using Mn3O4 nanoparticles","authors":"K.V. Jayaprasad, Titu Thomas, Manu Vaishakh, Sheenu Thomas","doi":"10.1016/j.physe.2025.116378","DOIUrl":"10.1016/j.physe.2025.116378","url":null,"abstract":"<div><div>The growing demand for efficient nonlinear optical (NLO) materials for photonic devices such as isolators, switches, and telecommunication components necessitates the exploration of new nanostructured systems. Transition metal oxides like Mn<sub>3</sub>O<sub>4</sub>, with strong electronic interactions and thermal responses, remain relatively underexplored for their NLO behavior. In this work, Mn<sub>3</sub>O<sub>4</sub> nanoparticles synthesized via ultrasonication-assisted precipitation were investigated using spatial self-phase modulation (SSPM) with a 532 nm CW DPSS laser. Structural and morphological characteristics were confirmed by XRD and TEM analyses. Nonlinear optical parameters, including the nonlinear refractive index (n<sub>2</sub>) and thermo-optic coefficient <span><math><mrow><mfrac><mtext>dn</mtext><mrow><mi>d</mi><mspace></mspace><mi>T</mi></mrow></mfrac></mrow></math></span> , were determined from the variation of SSPM patterns with laser intensity. Furthermore, a photonic diode based on a cascaded Mn<sub>3</sub>O<sub>4</sub>/TiO<sub>2</sub> hybrid structure was demonstrated, enabling nonreciprocal light propagation through unidirectional SSPM excitation. These findings highlight Mn<sub>3</sub>O<sub>4</sub> nanoparticles as promising candidates for NLO applications, while the proposed hybrid photonic diode offers potential in integrated optics, optical switching, and telecommunication technologies.</div></div>","PeriodicalId":20181,"journal":{"name":"Physica E-low-dimensional Systems & Nanostructures","volume":"175 ","pages":"Article 116378"},"PeriodicalIF":2.9,"publicationDate":"2025-09-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145220922","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 : 2025-09-23DOI: 10.1016/j.physe.2025.116379
A. Bahlaoui , Y. Zahidi
The paper discusses the Klein tunneling and Fabry–Pérot resonances of charge carriers through a rectangular potential barrier in twisted bilayer graphene. Within the framework of the low-energy excitations, the transmission probability and the conductance are obtained depending on the parameters of the problem. Owing to the moiré-induced anisotropy of the Hamiltonian in twisted bilayer graphene, the propagation of charge carriers exhibits an anisotropic behavior in Klein tunneling and Fabry–Pérot resonances. Moreover, we show that the anisotropy of the charge carriers induces asymmetry and deflection in the Fabry–Pérot resonances and Klein tunneling, and they are extremely sensitive to the height of the potential applied. Additionally, we found that the conductance is strongly sensitive to the barrier height but weakly sensitive to the barrier width. Therefore, it is possible to control the maxima and minima of the conductance of charge carriers in twisted bilayer graphene. With our results, we gain an in-depth understanding of tunneling properties in twisted bilayer graphene, which may help in the development and design of novel electronic nanodevices based on anisotropic 2D materials.
{"title":"Klein tunneling and Fabry–Pérot resonances in twisted bilayer graphene","authors":"A. Bahlaoui , Y. Zahidi","doi":"10.1016/j.physe.2025.116379","DOIUrl":"10.1016/j.physe.2025.116379","url":null,"abstract":"<div><div>The paper discusses the Klein tunneling and Fabry–Pérot resonances of charge carriers through a rectangular potential barrier in twisted bilayer graphene. Within the framework of the low-energy excitations, the transmission probability and the conductance are obtained depending on the parameters of the problem. Owing to the moiré-induced anisotropy of the Hamiltonian in twisted bilayer graphene, the propagation of charge carriers exhibits an anisotropic behavior in Klein tunneling and Fabry–Pérot resonances. Moreover, we show that the anisotropy of the charge carriers induces asymmetry and deflection in the Fabry–Pérot resonances and Klein tunneling, and they are extremely sensitive to the height of the potential applied. Additionally, we found that the conductance is strongly sensitive to the barrier height but weakly sensitive to the barrier width. Therefore, it is possible to control the maxima and minima of the conductance of charge carriers in twisted bilayer graphene. With our results, we gain an in-depth understanding of tunneling properties in twisted bilayer graphene, which may help in the development and design of novel electronic nanodevices based on anisotropic 2D materials.</div></div>","PeriodicalId":20181,"journal":{"name":"Physica E-low-dimensional Systems & Nanostructures","volume":"175 ","pages":"Article 116379"},"PeriodicalIF":2.9,"publicationDate":"2025-09-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145159088","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}
The strong visible photoluminescence (PL) in surface-oxidized nanostructured silicon emerges from the interplay between intrinsic Bloch states and oxide-related interfacial defects, making it difficult to isolate their role. Temperature-dependent PL measurements on nanostructured silicon with varying crystallite sizes manifest three distinct decay mechanisms involving band-to-band, band-to-trap and trap-to-trap transitions to multiple emission bands appearing in the convoluted broad PL spectrum. At lower temperatures , PL peak energy associated with the quantum-confined Bloch states exhibits a nearly linear blue shift, governed by a strong inverse power law dependence of the temperature coefficient on the effective crystallite size, while this trend reverses at higher temperatures. Conversely, the defect-related peak energies increase monotonically at a nearly constant rate throughout the experimental temperature range. A general analytical model for finite systems with a separable pseudo-potential effectively estimates the contributions from different decay channels to the PL emission. Theoretical results align well with the experimentally obtained values of the power-law exponents, offering a novel way to distinguish between the radiative recombination channels involving quantum-confined Bloch states and interfacial defects/trap states in nanostructured silicon.
{"title":"Temperature-dependent photoluminescence from nanostructured silicon: role of quantum-confined Bloch states and interfacial defects","authors":"Shayari Basu , Ujjwal Ghanta , Saddam Khan , Manotosh Pramanik , Rajalingam Thangavel , Bipul pal , Syed Minhaz Hossain","doi":"10.1016/j.physe.2025.116380","DOIUrl":"10.1016/j.physe.2025.116380","url":null,"abstract":"<div><div>The strong visible photoluminescence (PL) in surface-oxidized nanostructured silicon emerges from the interplay between intrinsic Bloch states and oxide-related interfacial defects, making it difficult to isolate their role. Temperature-dependent <span><math><mrow><mo>(</mo><mrow><mn>5</mn><mo>−</mo><mn>350</mn><mspace></mspace><mi>K</mi></mrow><mo>)</mo></mrow></math></span> PL measurements on nanostructured silicon with varying crystallite sizes manifest three distinct decay mechanisms involving band-to-band, band-to-trap and trap-to-trap transitions to multiple emission bands appearing in the convoluted broad PL spectrum. At lower temperatures <span><math><mfenced><mrow><mo>≲</mo><mn>225</mn><mspace></mspace><mi>K</mi></mrow></mfenced></math></span>, PL peak energy associated with the quantum-confined Bloch states exhibits a nearly linear blue shift, governed by a strong inverse power law dependence of the temperature coefficient on the effective crystallite size, while this trend reverses at higher temperatures. Conversely, the defect-related peak energies increase monotonically at a nearly constant rate throughout the experimental temperature range. A general analytical model for finite systems with a separable pseudo-potential effectively estimates the contributions from different decay channels to the PL emission. Theoretical results align well with the experimentally obtained values of the power-law exponents, offering a novel way to distinguish between the radiative recombination channels involving quantum-confined Bloch states and interfacial defects/trap states in nanostructured silicon.</div></div>","PeriodicalId":20181,"journal":{"name":"Physica E-low-dimensional Systems & Nanostructures","volume":"175 ","pages":"Article 116380"},"PeriodicalIF":2.9,"publicationDate":"2025-09-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145220921","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 : 2025-09-20DOI: 10.1016/j.physe.2025.116376
Morteza Torabi Rad, Ramin Karimian
This study demonstrates that tetrahexcarbon (THC) serves as an effective substrate for detecting toxic gases chlorine, phosgene, and mustard through non-covalent interactions. Density functional theory (DFT) calculations reveal excellent agreement with reference structures and size-dependent morphology (planar C60H28 vs. saddle-shaped C98H36). The THC substrate maintains a 3.83 eV band gap with 12 % reduction upon adsorption, while DOS, NBO, and ELF analyses confirm physisorption with minimal electronic perturbation. Adsorption energies follow reasonable pattern: mustard (-24.75 kcal mol-1) phosgene (-13.18 kcal mol-1) chlorine (-10.56 kcal mol-1), supported by QTAIM showing 2-11 bond critical points with positive . Chlorine exhibits superior sensitivity (9.11 × 1018 electrons/m3) and fast recovery (1.84 ns), enabling reusable detection, while mustard’s slow recovery (46.1 s) suggests single-use applications. Thermodynamics confirm spontaneous adsorption () with entropy trends reflecting molecular complexity, consistent with water interactions. Semi-empirical molecular dynamics (MD) simulations confirm the DFT-optimized configuration as the global minimum, with all sampled states showing higher energies and no chemical reactions, further validating THC’s physisorption capability for these toxic gases. These results position THC as a versatile platform for both real-time monitoring and one-time detection of chemical threats. Future work will investigate doping techniques to further optimize the properties of THC for applications in sensing, adsorption, and catalysis.
{"title":"Adsorption of toxic gases chlorine, phosgene, and mustard on tetrahexcarbon: DFT and semi-empirical MD studies","authors":"Morteza Torabi Rad, Ramin Karimian","doi":"10.1016/j.physe.2025.116376","DOIUrl":"10.1016/j.physe.2025.116376","url":null,"abstract":"<div><div>This study demonstrates that tetrahexcarbon (THC) serves as an effective substrate for detecting toxic gases chlorine, phosgene, and mustard through non-covalent interactions. Density functional theory (DFT) calculations reveal excellent agreement with reference structures and size-dependent morphology (planar C<sub>60</sub>H<sub>28</sub> vs. saddle-shaped C<sub>98</sub>H<sub>36</sub>). The THC substrate maintains a 3.83<!--> <!-->eV band gap with <span><math><mo><</mo></math></span>12<!--> <!-->% reduction upon adsorption, while DOS, NBO, and ELF analyses confirm physisorption with minimal electronic perturbation. Adsorption energies follow reasonable pattern: mustard (-24.75<!--> <!-->kcal<!--> <!-->mol<sup>-1</sup>) <span><math><mo>></mo></math></span> phosgene (-13.18<!--> <!-->kcal<!--> <!-->mol<sup>-1</sup>) <span><math><mo>></mo></math></span> chlorine (-10.56<!--> <!-->kcal<!--> <!-->mol<sup>-1</sup>), supported by QTAIM showing 2-11 bond critical points with positive <span><math><mrow><msup><mrow><mo>∇</mo></mrow><mrow><mn>2</mn></mrow></msup><mi>ρ</mi></mrow></math></span>. Chlorine exhibits superior sensitivity (9.11 × 10<sup>18</sup> electrons/m<sup>3</sup>) and fast recovery (1.84<!--> <!-->ns), enabling reusable detection, while mustard’s slow recovery (46.1<!--> <!-->s) suggests single-use applications. Thermodynamics confirm spontaneous adsorption (<span><math><mrow><mi>Δ</mi><mi>G</mi><mo><</mo><mn>0</mn></mrow></math></span>) with entropy trends reflecting molecular complexity, consistent with water interactions. Semi-empirical molecular dynamics (MD) simulations confirm the DFT-optimized configuration as the global minimum, with all sampled states showing higher energies and no chemical reactions, further validating THC’s physisorption capability for these toxic gases. These results position THC as a versatile platform for both real-time monitoring and one-time detection of chemical threats. Future work will investigate doping techniques to further optimize the properties of THC for applications in sensing, adsorption, and catalysis.</div></div>","PeriodicalId":20181,"journal":{"name":"Physica E-low-dimensional Systems & Nanostructures","volume":"175 ","pages":"Article 116376"},"PeriodicalIF":2.9,"publicationDate":"2025-09-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145159008","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 : 2025-09-18DOI: 10.1016/j.physe.2025.116355
Bruno Ipaves , Raphael B. de Oliveira , Guilherme da Silva Lopes Fabris , Matthias Batzill , Douglas S. Galvão
Understanding transition metal atoms’ intercalation and diffusion behavior in two-dimensional (2D) materials is essential for optimizing their performance in emerging applications. In this study, we used density functional tight binding (DFTB) simulations to investigate the atomic-scale mechanisms of manganese (Mn) intercalation into NbSe bilayers. Our results show that Mn prefers intercalated and embedded positions rather than surface adsorption, as cohesive energy calculations indicate enhanced stability in these configurations. Nudged elastic band (NEB) calculations revealed an energy barrier of 0.68 eV for the migration of Mn into the interlayer, comparable to other substrates, suggesting accessible diffusion pathways. Molecular dynamics (MD) simulations further demonstrated an intercalation concentration-dependent behavior. Mn atoms initially adsorb on the surface and gradually diffuse inward, resulting in an effective intercalation at higher Mn densities before clustering effects emerge. These results provide helpful insights into the diffusion pathways and stability of Mn atoms within NbSe bilayers, consistent with experimental observations and offering a deeper understanding of heteroatom intercalation mechanisms in transition metal dichalcogenides.
{"title":"Unraveling Mn intercalation and diffusion in NbSe2 bilayers through DFTB simulations","authors":"Bruno Ipaves , Raphael B. de Oliveira , Guilherme da Silva Lopes Fabris , Matthias Batzill , Douglas S. Galvão","doi":"10.1016/j.physe.2025.116355","DOIUrl":"10.1016/j.physe.2025.116355","url":null,"abstract":"<div><div>Understanding transition metal atoms’ intercalation and diffusion behavior in two-dimensional (2D) materials is essential for optimizing their performance in emerging applications. In this study, we used density functional tight binding (DFTB) simulations to investigate the atomic-scale mechanisms of manganese (Mn) intercalation into NbSe<span><math><msub><mrow></mrow><mrow><mn>2</mn></mrow></msub></math></span> bilayers. Our results show that Mn prefers intercalated and embedded positions rather than surface adsorption, as cohesive energy calculations indicate enhanced stability in these configurations. Nudged elastic band (NEB) calculations revealed an energy barrier of 0.68 eV for the migration of Mn into the interlayer, comparable to other substrates, suggesting accessible diffusion pathways. Molecular dynamics (MD) simulations further demonstrated an intercalation concentration-dependent behavior. Mn atoms initially adsorb on the surface and gradually diffuse inward, resulting in an effective intercalation at higher Mn densities before clustering effects emerge. These results provide helpful insights into the diffusion pathways and stability of Mn atoms within NbSe<span><math><msub><mrow></mrow><mrow><mn>2</mn></mrow></msub></math></span> bilayers, consistent with experimental observations and offering a deeper understanding of heteroatom intercalation mechanisms in transition metal dichalcogenides.</div></div>","PeriodicalId":20181,"journal":{"name":"Physica E-low-dimensional Systems & Nanostructures","volume":"175 ","pages":"Article 116355"},"PeriodicalIF":2.9,"publicationDate":"2025-09-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145106895","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}
京公网安备 11010802042870号
京ICP备2023020795号-1
扫码关注我们
求助内容：
应助结果提醒方式：