Physica E-low-dimensional Systems & Nanostructures最新文献

{"title":"A metasurface for linear-to-circular polarization conversion and sensing based on quasi-BIC","authors":"Fa-Zhan Liu,&nbsp;Si-Yuan Liao,&nbsp;Qi-Juan Li,&nbsp;Jing-Wei Huang,&nbsp;Hai-Feng Zhang","doi":"10.1016/j.physe.2024.116128","DOIUrl":"10.1016/j.physe.2024.116128","url":null,"abstract":"<div><div>This work presents a multifunctional metastructure (MS) which realizes linear to circular polarization conversion and sensing function based on quasi-bound states in the continuum (quasi-BIC). MS is made of silicon dioxide as substrate, and silicon as surface material, by etching cross holes and square holes on it to form a 2×2 structure, through the transmission of terahertz (THz) band, to form an ultrahigh quality factor (<em>Q</em>-factor), and realize the conversion of linearly polarized waves to circularly polarized ones. At 178.190 THz, it achieves a <em>Q</em> value of 2969, and in the range 178.193 TH to 178.200 THz, the axial ratio (AR) is less than 3 dB and the insertion loss is less than 0.0001. In addition, by changing the permittivity of the surrounding environment, the minimum of the output wave will produce a good linear frequency shift. Using this feature, the given device can also be used as a dielectric constant sensor to detect air quality. The device has a sensing sensitivity (<em>S</em>) of 6.415 THz RIU⁻¹ and a figure of merit (<em>FOM</em>) of 106.9. The parameters (<em>H</em>, <em>w</em>₂, <em>L</em>₂, <em>g</em>₂), incidence angle (<em>θ</em>) and the polarization angle (<em>φ</em>) are discussed. The effects of different parameters on the <em>Q</em>-factor and AR were analyzed, which helped to select the optimal parameters. The design can also be used in communication and biosensing.</div></div>","PeriodicalId":20181,"journal":{"name":"Physica E-low-dimensional Systems & Nanostructures","volume":"165 ","pages":"Article 116128"},"PeriodicalIF":2.9,"publicationDate":"2024-10-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142425336","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Design of spintronic devices based on adjustable half-metallicity induced by electric field in A-type antiferromagnetic bilayer NiI2","authors":"Shao-Chong Yin ,&nbsp;Jing-Xin Yu ,&nbsp;Xiu-Ying Liu ,&nbsp;Xiao-Dong Li ,&nbsp;Jing Chang","doi":"10.1016/j.physe.2024.116129","DOIUrl":"10.1016/j.physe.2024.116129","url":null,"abstract":"<div><div>Exploring the attainment of half-metallic behavior in two-dimensional (2D) materials through external perturbations is a popular area of current research. In this work, we demonstrate, using first-principles calculations, that bilayer NiI₂ (bi-NiI₂) is an A-type antiferromagnetic (AFM) semiconductor with an indirect bandgap of 0.86 eV, with the most stable configuration being the AB stacking mode. Upon the application of a vertical electric field, the material transforms from its original semiconducting state into a half-metallic state. Moreover, the spin polarization reverses its orientation whenever the direction of the electric field is altered. This intriguing behavior has inspired us to design a spintronic device based on the A-type AFM bi-NiI₂. By employing nonequilibrium Green's function (NEGF) combined with density functional theory (DFT) calculations, we find that the device achieves ON/OFF switching by applying vertical electric fields in parallel or anti-parallel configurations in the two leads. The device displays 100 % spin polarization in the parallel configuration (PC) scenario, driven by bias voltage or temperature differences. Utilizing either the parallel or antiparallel configuration (APC) for ON/OFF switching enables the device to exhibit tunneling magnetoresistance (TMR) of up to 1.45 × 10¹⁰ % due to bias voltage and up to 10¹¹ % thermal TMR arising from temperature differences between the leads. These findings highlight the potential of NiI₂ and A-type AFM bilayers in the design of spintronic devices.</div></div>","PeriodicalId":20181,"journal":{"name":"Physica E-low-dimensional Systems & Nanostructures","volume":"165 ","pages":"Article 116129"},"PeriodicalIF":2.9,"publicationDate":"2024-10-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142433333","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Resonant tunneling properties of laser dressed hyperbolic Pöschl-Teller double barrier potential","authors":"Mehmet Batı","doi":"10.1016/j.physe.2024.116126","DOIUrl":"10.1016/j.physe.2024.116126","url":null,"abstract":"<div><div>We examine the resonant tunneling properties of the laser-dressed hyperbolic Pöschl-Teller double quantum barrier structure. We use the non-equilibrium Green's function method to investigate structure parameters and electric field bias on the transmission properties of the system. The transmission probabilities and resonance energy levels are significantly influenced by the well widths and barrier heights. The barrier height increases, resonance energy levels shift toward higher values, and the resonance peak width narrows, leading to sharper and more selective tunneling behavior. Our results show that increasing the electric field bias leads to a decrease in the transmission probability at the first resonance peak, but this effect is not as strong for the subsequent peaks. Moreover, we find that changes in the laser field's parameter and structure parameters allow for fine control over the electronic spectra, allowing for modifications like red or blue shifts based on particular needs. The significance of comprehending the interaction among structural factors, external fields, and transmission qualities in quantum barrier structures is highlighted by our research, providing valuable information for the development and enhancement of electronic and optoelectronic systems with customized functionality. Our findings show the laser field has a considerable impact on resonant tunneling properties, opening the door to new device applications.</div></div>","PeriodicalId":20181,"journal":{"name":"Physica E-low-dimensional Systems & Nanostructures","volume":"165 ","pages":"Article 116126"},"PeriodicalIF":2.9,"publicationDate":"2024-10-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142425333","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Neutral donors confined in semiconductor coupled quantum dot-rings: Position-dependent properties and optical transparency phenomenon","authors":"N. Hernández ,&nbsp;R.A. López-Doria ,&nbsp;Y.A. Suaza ,&nbsp;M.R. Fulla","doi":"10.1016/j.physe.2024.116122","DOIUrl":"10.1016/j.physe.2024.116122","url":null,"abstract":"<div><div>Electronic properties of a neutral donor confined in a <span><math><mi>GaAs</mi></math></span> coupled quantum dot-ring covered by a <span><math><mrow><msub><mrow><mi>Al</mi></mrow><mrow><mn>0</mn><mo>.</mo><mn>3</mn></mrow></msub><msub><mrow><mi>Ga</mi></mrow><mrow><mn>0</mn><mo>.</mo><mn>7</mn></mrow></msub><mi>As</mi></mrow></math></span> matrix were calculated using the finite element method under the effective mass and the envelope function approximations. The proposed model is set up to fit a realistic coupled quantum dot-ring geometry revealed by atomic force microscopy images. The results show that the energy levels and the transition energies in the presence of an electric field strongly depend on the donor center’s angular position. Furthermore, the total optical absorption coefficient is calculated within the two-level approximation and the matrix density formalism. The absorption spectrum shows that the system can be tuned between 5 and <span><math><mrow><mn>30</mn><mspace></mspace><mi>meV</mi></mrow></math></span>. Also, an optical transparency effect for different configurations characterized by specific donor center’s angular positions and electric field values is seen. Finally, a novel redshift is observed when the sample temperature increases.</div></div>","PeriodicalId":20181,"journal":{"name":"Physica E-low-dimensional Systems & Nanostructures","volume":"165 ","pages":"Article 116122"},"PeriodicalIF":2.9,"publicationDate":"2024-10-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142425334","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Correlation of Valence electron structure and properties of monolayer graphene and MX2 (M=Mo, W; X=S, Se, Te): Empirical Electron Theory (EET) investigation","authors":"Xinze Wang,&nbsp;Yongquan Guo,&nbsp;Boyang Li,&nbsp;Yichen Feng,&nbsp;Wei Tang","doi":"10.1016/j.physe.2024.116124","DOIUrl":"10.1016/j.physe.2024.116124","url":null,"abstract":"<div><div>The atomically thin layers of transition-metal dichalcogenide (TMDC) materials have garnered considerable attention due to their exceptional electrical, optical, mechanical, and thermal properties. Hence, it is important to investigate the mechanism of their excellent properties. In this paper, the study is focused on the correlation between valence electron structures (VESs) and mechanical as well as thermal properties of graphene and MX₂ (M = Mo, W; X = S, Se, Te) for revealing their essential mechanisms of properties with an empirical electron theory (EET). A model of Young's modulus is built for the monolayer graphene and MX₂ (M = Mo, W; X = S, Se, Te) based on the VES, which has been verified by the observed ones of elements in the 4th to 6th periods in the periodic table of elements. The calculated bond lengths and mechanical and thermal properties of graphene and MX₂ are in good agreement with experimental ones. The study reveals that the thermal and mechanical properties of MX₂ strongly depend on their valence electron structures. It shows that the melting point, cohesive energy, thermal conductivity, and Young's modulus are modulated by covalence electron pair <em>n</em>_<em>A</em>, the averaged covalence electron per atom <em>n</em>_<em>c</em>/atom, covalence electron pair <em>n</em>_<em>A</em> and linear density of covalent electron on the strongest bond <em>ρ</em>_<em>l</em>, respectively. The study helps explain the thermal and mechanical properties of two-dimensional (2D) materials and also supplies a reference for their design with high performance by modulating their valence electron structures.</div></div>","PeriodicalId":20181,"journal":{"name":"Physica E-low-dimensional Systems & Nanostructures","volume":"165 ","pages":"Article 116124"},"PeriodicalIF":2.9,"publicationDate":"2024-10-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142425335","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Multi-layer nanoring array-based ultra-wideband solar absorber for photothermal conversion","authors":"Jiaxing Jiang ,&nbsp;Yingting Yi ,&nbsp;Qianju Song ,&nbsp;Zao Yi ,&nbsp;Can Ma ,&nbsp;Qingdong Zeng ,&nbsp;Tangyou Sun ,&nbsp;Shubo Cheng ,&nbsp;Yougen Yi ,&nbsp;Majid Niaz Akhtar","doi":"10.1016/j.physe.2024.116123","DOIUrl":"10.1016/j.physe.2024.116123","url":null,"abstract":"<div><div>In this work, based on the finite difference time domain method, we propose and investigate an efficient nanoscale solar absorber based on multilayer nanorings. The absorber is made up of a 4-layer TiO₂-TiN nanoring array, a TiO₂ insulating layer and a Ti substrate, all of which are high-melting materials. The absorber exhibits an absorption efficiency surpassing 95 % across a wavelength span of 280–4000 nm, thereby attaining a bandwidth of 3720 nm. Additionally, it maintains an average absorption efficiency of 98.8 % throughout the entire wavelength spectrum. Furthermore, calculations reveal that the absorber possesses a solar spectrum-weighted absorption of up to 99 %. The analysis of the electric field distribution indicates that the observed intense absorption is attributed to the plasmonic resonance phenomenon, along with the near-field coupling effects exhibited by the multi-turn nanorings. In addition, our calculations revealed a remarkably high thermal radiation efficiency for this absorber, specifically 99.2 % at 2000 K and 98.9 % at 1500 K, respectively. Therefore, we then calculated the photothermal conversion efficiency of the absorber. At the solar concentration factor C = 1000, the photothermal conversion efficiency surpasses 90 % across the entire temperature range. At C = 100, it is still greater than 80 % at 1000 K. At C = 10, it is still greater than 80 % at 700 K. And at C = 1, it is still greater than 80 % at 500 K. These results indicate that absorbers can be used in a variety of environments. Furthermore, the absorber sustains its superior absorption capabilities at wider solar radiation angles, demonstrating insensitive properties to polarization variations and robust tolerance to manufacturing inaccuracies. These exceptional attributes render it highly suited for diverse applications in solar energy harvesting and photothermal transformation.</div></div>","PeriodicalId":20181,"journal":{"name":"Physica E-low-dimensional Systems & Nanostructures","volume":"165 ","pages":"Article 116123"},"PeriodicalIF":2.9,"publicationDate":"2024-10-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142534818","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}

{"title":"Superconductivity and spin density wave in AA stacked bilayer graphene","authors":"A.O. Sboychakov,&nbsp;A.L. Rakhmanov,&nbsp;A.V. Rozhkov","doi":"10.1016/j.physe.2024.116118","DOIUrl":"10.1016/j.physe.2024.116118","url":null,"abstract":"<div><div>This work theoretically analyzes electronic ordering in AA-stacked bilayer graphene and the role of the Coulomb interaction in these many-body phenomena. Using the random phase approximation to account for screening, we find intra-layer effective interactions to be much stronger than inter-layer interactions; under certain circumstances, the latter may also become attractive. At zero doping, the Coulomb repulsion stabilizes the spin-density wave state, with a Néel temperature in the tens of Kelvin. While dominant in the undoped system, the spin-density wave is destroyed by sufficiently strong doping and a superconducting phase emerges. We find that the effective Coulomb inter-layer interaction can give rise to superconductivity. However, the corresponding critical temperature is negligibly small, and phonon-mediated attraction must be introduced to observe it. Strong intra-layer repulsion suppresses order parameters that couple two intra-layer electrons. We point out a possible superconducting state with finite Cooper pair momentum.</div></div>","PeriodicalId":20181,"journal":{"name":"Physica E-low-dimensional Systems & Nanostructures","volume":"165 ","pages":"Article 116118"},"PeriodicalIF":2.9,"publicationDate":"2024-10-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142425337","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}

{"title":"Generation of femtosecond spin-polarized current pulses at Fe/MgO interface by quasi-static voltage","authors":"Piotr Graczyk ,&nbsp;Maria Pugaczowa-Michalska ,&nbsp;Maciej Krawczyk","doi":"10.1016/j.physe.2024.116120","DOIUrl":"10.1016/j.physe.2024.116120","url":null,"abstract":"<div><div>The generation of short spin-current pulses is essential for fast spintronic devices. So far, spin current pulses are generated by femtosecond laser pulses which drive spins from a ferromagnetic metal layer. However, the need for miniaturization, simplicity and energy efficiency favour electric-field control of spintronic devices over optic or thermal control. Here, we combine ab initio calculations of electronic density of states at MgO/Fe interface with continuous model for charge transport to investigate the dynamics of the spin-dependent potential. We demonstrate that the voltage-driven instability of the electronic band structure due to the electronic resonant states at the Fe/MgO interface results in the generation of the femtosecond spin-polarized current pulse with the spin polarization up to <span><math><mrow><mi>P</mi><mo>=</mo><mn>7</mn></mrow></math></span> 00 % that propagates from the interface to the bulk. The dynamics of the current pulses driven by the Stoner instability depends neither on the dielectric relaxation time nor on the details of how the instability is achieved by changing the voltage, i.e. as long as the voltage changes are slow (quasi-static) with respect to the time determined by the spin diffusion constant, being of the order of fs. The presence of the instability can be detected by THz time-domain spectroscopy or pump-probe techniques.</div></div>","PeriodicalId":20181,"journal":{"name":"Physica E-low-dimensional Systems & Nanostructures","volume":"165 ","pages":"Article 116120"},"PeriodicalIF":2.9,"publicationDate":"2024-10-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142425063","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Thermoelectric properties of MoS2-MoTe2 and MoS2-MoSe2lateral hetero-structures: The effects of external magnetic, transverse electric fields and nanoribbon width","authors":"Mona Abdi ,&nbsp;Bandar Astinchap ,&nbsp;Farhad Khoeini","doi":"10.1016/j.physe.2024.116119","DOIUrl":"10.1016/j.physe.2024.116119","url":null,"abstract":"<div><div>Extensive research is underway to improve the thermoelectric properties of materials by enhancing the figure of merit (ZT). In this study, we are investigating the thermoelectric properties of MoS₂/MoTe₂ and MoS₂/MoSe₂ lateral heterostructures (LH-S) under the influence of external magnetic fields (EMF) and transverse electric fields (TEF). We employ the non-equilibrium Green's function (N-EGF) and tight-binding (TB) methods for our analysis. The results obtained indicate that the ZT for MoS₂-MoTe₂ and MoS₂-MoSe₂ LH-S enhanced with an increase in the TEF. The ZT of MoS₂-MoSe₂ LH-S increases near room temperature, while the ZT of MoS₂-MoTe₂ LH-S increases with an increase in EMF across the entire temperature range. Additionally, the ZT for MoS₂-MoSe₂ LH-S increases with an increase in the nanoribbon width, whereas for MoS₂-MoTe₂ LH-S, it decreases. The results reveal that the semiconductor type of MoS₂-MoSe₂ and MoS₂-MoTe₂ LH-S changes from n-type to p-type when subjected to EMF and transverse TEF. The examination of the temperature dependence of ZT in the presence of TEF and EMF for MoS₂-MoTe₂ and MoS₂-MoSe₂ LH-S indicates that these structures are highly promising candidates for use in electrical devices.</div></div>","PeriodicalId":20181,"journal":{"name":"Physica E-low-dimensional Systems & Nanostructures","volume":"165 ","pages":"Article 116119"},"PeriodicalIF":2.9,"publicationDate":"2024-10-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142425343","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}

{"title":"Transport through a monolayer-tube junction: Sheet-to-tube spin current","authors":"Yuma Kitagawa ,&nbsp;Yuta Suzuki ,&nbsp;Shin-ichiro Tezuka ,&nbsp;Hiroshi Akera","doi":"10.1016/j.physe.2024.116111","DOIUrl":"10.1016/j.physe.2024.116111","url":null,"abstract":"<div><div>We develop a method to calculate the electron flow between an arbitrary atomic monolayer sheet and an arbitrary tube by expressing the corresponding sheet-tube tunneling matrix elements with those between sheets. We use this method to calculate the spin current from a monolayer silicene sheet with sublattice-staggered current-induced spin polarization to a silicene tube. The calculated sheet-to-tube spin current exhibits an oscillation as a function of the tube circumferential length because the Fermi points in the tube cross the Fermi circle in the sheet. Furthermore, the spin current with spin in the out-of-plane direction, which is absent in the sheet-sheet junction (including twisted sheets) with <span><math><msub><mrow><mi>C</mi></mrow><mrow><mn>3</mn></mrow></msub></math></span> rotational symmetry, appears in an oscillating form in the tube-sheet junction due to the broken <span><math><msub><mrow><mi>C</mi></mrow><mrow><mn>3</mn></mrow></msub></math></span> rotational symmetry. This is an example of the symmetry manipulation which realizes switching a particular component of the spin current.</div></div>","PeriodicalId":20181,"journal":{"name":"Physica E-low-dimensional Systems & Nanostructures","volume":"165 ","pages":"Article 116111"},"PeriodicalIF":2.9,"publicationDate":"2024-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142425064","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}