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

英文中文

GST and BFO assisted microring resonator for nanoplasmonic applications 用于纳米光子学应用的 GST 和 BFO 辅助微孔谐振器

IF 2.9 3区物理与天体物理 Q3 NANOSCIENCE & NANOTECHNOLOGY

Physica E-low-dimensional Systems & Nanostructures

Pub Date : 2024-11-09 DOI: 10.1016/j.physe.2024.116149

Diksha Chauhan , Zen Sbeah , Vishal Sorathiya , Amita Verma , Ram Prakash Dwivedi

In this paper a Metal-Insulator-Metal configuration based electro-optic microring resonator is designed and simulated by using Bismuth Ferrite and Germanium Antimony Telluride for wavelength filtering, switching and modulator applications. The device works on the phenomena of change in refractive index of the active materials when electric field is applied. Initially, switching and filtering is demonstrated by using bismuth ferrite as an active material inside the ring resonator. Later on, an additional layer of GST is added to the ring resonator resulting in increased light confinement inside the ring resonator in the amorphous state of GST layer. Due to this, resonant dips sharpens which improves the quality factor of the device up to 154. By optimizing the device's structural parameters, a modulation depth of 23.11 dB is achieved with a low loss of 1.6 dB. Additionally, these innovative SPPs plasmonic waveguide structures can accommodate various filtering requirements and have good filtering efficiency.

本文利用铁氧体铋和碲化锗锑设计并模拟了一种基于金属-绝缘体-金属配置的电光微波谐振器，用于波长滤波、开关和调制器应用。该装置利用施加电场时活性材料折射率变化的现象工作。最初，通过在环形谐振器内使用铁氧体铋作为活性材料来演示开关和滤波。后来，在环形谐振器中又添加了一层 GST，从而在 GST 层的非晶态下增加了环形谐振器内部的光局限性。因此，谐振骤降变得尖锐，从而将器件的品质因数提高到 154。通过优化器件的结构参数，可实现 23.11 dB 的调制深度和 1.6 dB 的低损耗。此外，这些创新的 SPPs 质子波导结构还能满足各种滤波要求，并具有良好的滤波效率。

引用次数: 0

Josephson and thermophase effect in interacting T-shaped double quantum dots system 相互作用的 T 型双量子点系统中的约瑟夫森效应和热相效应

IF 2.9 3区物理与天体物理 Q3 NANOSCIENCE & NANOTECHNOLOGY

Physica E-low-dimensional Systems & Nanostructures

Pub Date : 2024-11-08 DOI: 10.1016/j.physe.2024.116142

Bhupendra Kumar, Sachin Verma, Ajay

This article theoretically analyzes the phase and thermal driven transport properties in a T-shaped double quantum dot Josephson junction. We began by investigating the Josephson current for different on-dot Coulomb interaction on central quantum dot and interdot-tunneling between quantum dots. Josephson current exhibits

0 - π

phase transition for intermediate Coulomb interaction to dot-lead coupling ratio with quantum dots energy level below the Fermi level. The Josephson current exhibits complete

π

-phase in doublet regime for relatively large Coulomb interaction to dot-lead coupling ratio. The interdot-tunneling destroys the

π

region and shifts the

0 - π

transition points depending on the position of quantum dot energy levels. Further, depending on the position of central quantum dot energy level and Coulomb interaction strength, Josephson current shows Fano types symmetric and asymmetric line shapes with a Fano dip at the Fermi level of side dot. Next, we demonstrated that with increasing thermal energy, the discontinuity in the Josephson current smeared and becomes sinusoidal. Finally, the total current (Josephson current+quasi-particle current) is analyzed by applying a finite temperature biasing across the junction. The system is examined in electrically open circuit configuration, where phase driven Josephson current and thermal driven quasi-particle cancels each other, and analyze the thermophase Seebeck effect in linear response region. At the

0 - π

transition points, where the Josephson current shows discontinuities, the thermal gradient produces abrupt thermophase Seebeck coefficient (TPSC) peaks, and the strength of interdot-tunneling provides great control over these abrupt TPSC peaks.

本文从理论上分析了 T 型双量子点约瑟夫森结的相位和热驱动传输特性。我们首先研究了中心量子点上不同点上库仑相互作用和量子点间隧道的约瑟夫森电流。在量子点能级低于费米级的情况下，约瑟夫森电流在库仑相互作用与点-引线耦合比中间呈现 0-π 相变。当库仑相互作用与点-铅耦合比相对较大时，约瑟夫森电流在双态中表现出完全的π相。点间隧道破坏了 π 区域，并根据量子点能级的位置移动了 0-π 转换点。此外，根据中心量子点能级的位置和库仑相互作用强度的不同，约瑟夫森电流显示出法诺类型的对称和不对称线形，并在侧点的费米级出现法诺凹陷。接着，我们证明了随着热能的增加，约瑟夫森电流的不连续性会逐渐消失，变成正弦波。最后，通过在结点上施加有限温度偏压，分析了总电流（约瑟夫森电流+准粒子电流）。该系统在电气开路配置下进行研究，其中相位驱动的约瑟夫森电流和热驱动的准粒子电流相互抵消，并分析线性响应区域的热相塞贝克效应。在约瑟夫森电流显示不连续的 0-π 过渡点，热梯度会产生突变的热相塞贝克系数 (TPSC) 峰值，而隧道间的强度可极大地控制这些突变的 TPSC 峰值。

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引用次数: 0

Photonic modes in twisted graphene nanoribbons 扭曲石墨烯纳米带中的光子模式

IF 2.9 3区物理与天体物理 Q3 NANOSCIENCE & NANOTECHNOLOGY

Physica E-low-dimensional Systems & Nanostructures

Pub Date : 2024-11-08 DOI: 10.1016/j.physe.2024.116146

Abdullah Guvendi , Semra Gurtas Dogan , Omar Mustafa , Kobra Hasanirokh

This study investigates the behavior of photonic modes in twisted graphene nanoribbons (TGNRs) using an analytical approach based on solving the fully covariant vector boson equation. We present a model that demonstrates how helical twisting in TGNRs significantly affects the evolution of photonic modes. Our analytical solutions yield detailed expressions for mode profiles, energy spectra, and decay characteristics. We find that increasing the twist parameter shortens the decay times (

τ_{n s}

) for damped modes, indicating enhanced photonic coupling due to the twisted geometry. Conversely, longer nanoribbons (NRs) exhibit increased decay times, showing a length (

L

)-dependent effect, where

τ_{n s} \propto L / c

, with

c

representing the speed of light. These findings may enhance the understanding of light control in nanostructures and suggest potential applications in tunable photonic devices, topological photonics, and quantum optical systems.

本研究采用基于求解全协变矢量玻色子方程的分析方法，研究了扭曲石墨烯纳米带（TGNR）中的光子模式行为。我们提出的模型证明了 TGNR 中的螺旋扭曲如何显著影响光子模式的演化。我们的分析解得出了模式剖面、能谱和衰变特性的详细表达式。我们发现，增加扭曲参数会缩短阻尼模式的衰减时间（τns），这表明扭曲几何形状增强了光子耦合。相反，较长的纳米带（NR）的衰减时间会增加，显示出长度（L）依赖效应，其中τns∝L/c，c代表光速。这些发现可以加深人们对纳米结构中光控制的理解，并为可调谐光子器件、拓扑光子学和量子光学系统的潜在应用提供了建议。

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引用次数: 0

Uncovering bound states in the continuum in InSb nanowire networks 揭示 InSb 纳米线网络中的连续束缚态

IF 2.9 3区物理与天体物理 Q3 NANOSCIENCE & NANOTECHNOLOGY

Physica E-low-dimensional Systems & Nanostructures

Pub Date : 2024-11-07 DOI: 10.1016/j.physe.2024.116145

D. Martínez , P.A. Orellana , L. Rosales , J. Dolado , M. Amado , E. Diez , F. Domínguez-Adame , R.P.A. Lima

Bound states in the continuum (BICs) are exotic, localized states even though their energy lies in the continuum spectra. Since its discovery in 1929, the quest to unveil these exotic states in charge transport experiments remains an active pursuit in condensed matter physics. Here, we study charge transport in InSb nanowire networks in the ballistic regime and subject to a perpendicular magnetic field as ideal candidates to observe and control the appearance of BICs. We find that BICs reveal themselves as distinctive resonances or antiresonances in the conductance by varying the applied magnetic field and the Fermi energy. We systematically consider different lead connections in hashtag-like nanowire networks, finding the optimal configuration that enhances the features associated with the emergence of BICs. Finally, the investigation focuses on the effect of the Rashba spin–orbit interaction of InSb on the occurrence of BICs in nanowire networks. While the interaction generally plays a detrimental role in the signatures of the BICs in the conductance of the nanowire networks, it opens the possibility to operate these nanostructures as spin filters for spintronics. We believe that this work could pave the way for the unambiguous observation of BICs in charge transport experiments and for the development of advanced spintronic devices.

连续谱中的束缚态（BIC）是一种奇异的局部态，尽管其能量位于连续谱中。自 1929 年被发现以来，在电荷输运实验中揭示这些奇异态的探索一直是凝聚态物理学中的一项积极追求。在这里，我们研究了弹道机制下 InSb 纳米线网络中的电荷传输，并将其作为观察和控制 BIC 出现的理想候选。我们发现，通过改变外加磁场和费米能，BIC 在电导中表现为独特的共振或反共振。我们系统地考虑了哈希标签状纳米线网络中不同的引线连接，找到了能增强与 BIC 出现相关的特征的最佳配置。最后，我们重点研究了 InSb 的 Rashba 自旋轨道相互作用对纳米线网络中出现 BIC 的影响。虽然这种相互作用通常对纳米线网络电导中的 BIC 起着不利作用，但它为将这些纳米结构用作自旋电子学的自旋过滤器提供了可能性。我们相信，这项工作将为在电荷传输实验中明确观测 BIC 以及开发先进的自旋电子器件铺平道路。

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引用次数: 0

Enhanced piezoelectricity induced by transition metal atoms adsorption on monolayer and bilayer MoS2 单层和双层 MoS2 上吸附过渡金属原子诱导的增强压电性

IF 2.9 3区物理与天体物理 Q3 NANOSCIENCE & NANOTECHNOLOGY

Physica E-low-dimensional Systems & Nanostructures

Pub Date : 2024-11-06 DOI: 10.1016/j.physe.2024.116148

Xinxin Wang, Gaojie Li, Xiaofei Wang, Weiwei Ju, Xiaohong Li

Piezoelectricity in MoS₂ has attracted extensive attention because of potential applications in energy harvesting and sensors. However, the piezoelectricity of MoS₂ monolayer is weaker than those of traditional piezoelectric materials. Here, based on first principles calculations, we report the large work function transition metal atoms (TMs = Ni, Pd, Pt and Ir) adsorbed on monolayer and bilayer MoS₂ with large out-of-plane piezoelectric polarization. For TMs adsorbed on monolayer MoS₂, the Ir and Ni adsorption exhibit stronger adsorption energy and larger migration barrier compared with Pd and Pt adsorption. All structures maintain dynamical stability at 300 K and exhibit p-type semiconducting band structures. The larger out-of-plane piezoelectric coefficients induced by adsorption increase with increasing the adsorption concentration, accompanied with slightly decreased in-plane piezoelectric coefficients, which is attributed to more and more electrons participating in redistribution along the out-of-plane direction. For TMs adsorbed bilayer MoS₂, the energetically favorable configuration has same polarization orientation between two monolayers, which results in increased in-plane piezoelectric coefficients. The out-of-plane piezoelectric coefficients further increase due to the coupling of interlayer vertical polarization and TMs adsorption induced vertical polarization. Our results provide a possible way to increase the piezoelectricity of MoS₂.

MoS2 的压电性因其在能量收集和传感器中的潜在应用而受到广泛关注。然而，与传统压电材料相比，MoS2 单层的压电性较弱。在此，我们基于第一性原理计算，报道了吸附在单层和双层 MoS2 上的大功函数过渡金属原子（TMs = Ni、Pd、Pt 和 Ir）具有较大的面外压电极化。对于吸附在单层 MoS2 上的 TMs，与吸附 Pd 和 Pt 相比，吸附 Ir 和 Ni 表现出更强的吸附能和更大的迁移势垒。所有结构在 300 K 时都能保持动态稳定，并表现出 p 型半导体带结构。吸附引起的面外压电系数随吸附浓度的增加而增大，同时面内压电系数略有下降，这是因为越来越多的电子沿面外方向参与了再分布。对于吸附了 TMs 的双层 MoS2，能量上有利的构型是两个单层之间具有相同的极化方向，从而导致面内压电系数增大。由于层间垂直极化和 TMs 吸附引起的垂直极化的耦合作用，面外压电系数进一步增加。我们的研究结果为提高 MoS2 的压电性提供了一种可能的方法。

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引用次数: 0

Giant excitonic magneto-Stark effect in wide GaAs/AlGaAs quantum wells 宽砷化镓/砷化镓量子阱中的巨激子磁-斯塔克效应

IF 2.9 3区物理与天体物理 Q3 NANOSCIENCE & NANOTECHNOLOGY

Physica E-low-dimensional Systems & Nanostructures

Pub Date : 2024-10-31 DOI: 10.1016/j.physe.2024.116134

D.K. Loginov, I.V. Ignatiev

We have studied the magneto-Stark effect of exciton states with large wave vectors, significantly exceeding the wave vector of light. This magneto-Stark effect can be called “giant” in comparison with a similar effect observed in bulk materials in comparable magnetic fields. In this work, we propose a microscopic model of the “giant” magneto-Stark effect. The model does not contain any free parameters. The numerical results obtained in the framework of this model quantitatively describe the experimental results published earlier in Ref. S. Y. Bodnar et al., (2017) for a heterostructure with a wide GaAs/AlGaAs quantum well in a magnetic field.

我们研究了激子态的磁-斯塔克效应，其波矢量很大，大大超过了光的波矢量。与在同类磁场中观察到的块体材料的类似效应相比，这种磁-斯塔克效应可称为 "巨 "效应。在这项工作中，我们提出了一个 "巨型 "磁-斯塔克效应的微观模型。该模型不包含任何自由参数。在该模型框架下获得的数值结果定量地描述了早先发表在 Ref.S. Y. Bodnar 等人（2017 年）发表的关于磁场中具有宽 GaAs/AlGaAs 量子阱的异质结构的实验结果。

引用次数: 0

Fluorinated carbon nanotube-insulator–metal diodes: Predictions from first-principles calculations 氟化碳纳米管-绝缘体-金属二极管：第一原理计算预测

IF 2.9 3区物理与天体物理 Q3 NANOSCIENCE & NANOTECHNOLOGY

Physica E-low-dimensional Systems & Nanostructures

Pub Date : 2024-10-30 DOI: 10.1016/j.physe.2024.116133

G.R. Berdiyorov

Using quantum transport calculations with the Atomistix Toolkit, we propose carbon nanotube (CNT)-based diode structures featuring enhanced diode properties. The idea is to use a CNT with a fluorinated tip, which is separated from the metallic electrode by an insulating (ZnO) layer. This system shows better operational properties in terms of both current magnitude and current rectification compared to diode structures consisting of non-fluorinated CNTs. The enhanced current rectification is related to the formation of additional voltage-polarity-dependent transmission channels. The proposed system can be used to create CNT-based rectenna devices with enhanced solar conversion efficiency.

通过使用 Atomistix 工具包进行量子输运计算，我们提出了基于碳纳米管 (CNT) 的二极管结构，该结构具有增强的二极管特性。我们的想法是使用带有氟化尖端的碳纳米管，并用绝缘（氧化锌）层将其与金属电极隔开。与由非氟化碳纳米管组成的二极管结构相比，该系统在电流大小和电流整流方面都显示出更好的工作特性。电流整流的增强与附加电压极性传输通道的形成有关。所提出的系统可用于制造基于碳纳米管的整流天线器件，从而提高太阳能转换效率。

引用次数: 0

Single-layer black phosphorus-enhanced narrowband perfect absorber in the terahertz range 太赫兹范围内的单层黑磷增强型窄带完美吸收器

IF 2.9 3区物理与天体物理 Q3 NANOSCIENCE & NANOTECHNOLOGY

Physica E-low-dimensional Systems & Nanostructures

Pub Date : 2024-10-29 DOI: 10.1016/j.physe.2024.116144

Pengfei Sun , Lijing Su , Sihan Nie , Xin Li , Yaxin Zhou , Yang Gao

In this paper, a narrowband absorber based on black phosphorus (BP) is proposed. By utilizing a single-layer BP, a Si structure with four etched holes, and a perfectly electrically conductive (PEC) plate, multi-band absorption can be achieved in the range of 3.8 THz to 5.0 THz. The location and absorbance of the three peaks are 4.32 THz (99.7 %), 4.53 THz (95.6 %), and 4.69 THz (56.7 %), respectively. The anisotropy of the BP structure leads to different absorption spectra when illuminated by TE and TM polarized light sources. Altering the electron doping in BP allows control over the position and intensity of absorption peaks. Upon examining the electric field distribution of the absorber, it is evident that the dominant physical mechanism is the localized surface plasmon resonance (LSPR). Overall, the monolayer BP absorber designed in this study can be utilized to construct a polarimetric sensor for infrared wavelengths. Additionally, it provides a valuable reference for 2D anisotropic plasma devices.

本文提出了一种基于黑磷 (BP) 的窄带吸收器。通过利用单层 BP、带有四个蚀刻孔的硅结构和完全导电 (PEC) 板，可实现 3.8 THz 至 5.0 THz 范围内的多波段吸收。三个峰值的位置和吸收率分别为 4.32 THz (99.7%)、4.53 THz (95.6%) 和 4.69 THz (56.7%)。当 TE 和 TM 偏振光源照射时，BP 结构的各向异性会导致不同的吸收光谱。改变 BP 中的电子掺杂量可以控制吸收峰的位置和强度。通过研究吸收体的电场分布，可以明显看出主导物理机制是局部表面等离子体共振（LSPR）。总之，本研究设计的单层 BP 吸收体可用于构建红外波长的极性传感器。此外，它还为二维各向异性等离子体设备提供了有价值的参考。

引用次数: 0

Type-II induced quantum confinement in type-I heterostructured semiconductor nanowires I 型异质结构半导体纳米线中的 II 型诱导量子约束

IF 2.9 3区物理与天体物理 Q3 NANOSCIENCE & NANOTECHNOLOGY

Physica E-low-dimensional Systems & Nanostructures

Pub Date : 2024-10-28 DOI: 10.1016/j.physe.2024.116132

Temerson F.O. Lara , Diego R. da Costa , Alice R. de Almeida , Ariel A. de Sousa , André J. Chaves , Andrey Chaves , Teldo A.S. Pereira

We theoretically investigate the electronic properties of semiconductor nanowires with axial heterostructure. We employ the effective mass approximation within envelope wavefunction formalism to analyze the behavior of charge carriers in nanowires composed of two semiconductor materials with different energy gaps, grown along the wire axis, with a cylindrically symmetric shape. We start by considering a type-I band alignment, resulting in the formation of a quantum well structure. Then, we demonstrate that modifications in the effective mass and the structural parameters of the system make it possible to change the type of the band alignment, thus dictating the carrier confinement. For certain values of the wire radius and the ratio of effective masses between the well and barrier regions, the contribution of the kinetic energy term to the total effective confinement potential becomes predominant compared to the mismatched band potential. This leads to a switching in the preferential spatial distribution of the wave functions towards the barrier region, exhibiting characteristics of a type-II induced axial junction.

我们从理论上研究了具有轴向异质结构的半导体纳米线的电子特性。我们采用包络波函数形式主义中的有效质量近似来分析电荷载流子在由两种具有不同能隙的半导体材料组成的纳米线中的行为，这些纳米线沿着线轴生长，具有圆柱对称的形状。我们首先考虑 I 型带排列，从而形成量子阱结构。然后，我们证明，通过改变系统的有效质量和结构参数，可以改变带排列的类型，从而决定载流子约束。对于一定的线半径值以及阱区和势垒区之间的有效质量比，动能项对总有效禁锢势的贡献与失配带势相比变得占主导地位。这导致波函数的优先空间分布转向势垒区，表现出 II 型诱导轴向结的特征。

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引用次数: 0

Yu-Shiba-Rusinov bound states boost surface odd-frequency pairing Yu-Shiba-Rusinov 边界态促进表面奇频配对

IF 2.9 3区物理与天体物理 Q3 NANOSCIENCE & NANOTECHNOLOGY

Physica E-low-dimensional Systems & Nanostructures

Pub Date : 2024-10-26 DOI: 10.1016/j.physe.2024.116127

Subhajit Pal, Colin Benjamin

We predict that the appearance of zero-energy Yu-Shiba-Rusinov(YSR) bound states in two different setups, metal-spin flipper-metal-s-wave superconductor (

N_{1} - s f - N_{2} - S

) and superconductor-metal-spin flipper-metal-superconductor (

S - N_{1} - s f - N_{2} - S

) junctions, can cause a multi-fold enhancement of surface odd-frequency superconducting pairing. On the other hand, in the absence of these bound states, even-frequency pairing dominates surface odd-frequency pairing. Specifically, in the

S - N_{1} - s f - N_{2} - S

Josephson junction, the emergence of zero energy YSR bound states leads to a

0 - π

junction transition and surface odd-frequency pairing dominance. Notably, odd-frequency pairing vanishes in the absence of the YSR-bound states. Interestingly, the equal spin–triplet pairing is the dominant component in odd-frequency superconductivity in both setups, which could have important implications for superconducting spintronics. Overall, our findings may help to detect the presence of YSR-bound states through the observation of surface odd-frequency pairing and contribute to a better understanding of their relationship.

我们预测，在金属-自旋翻转器-金属-S 波超导体（N1-sf-N2-S）和超导体-金属-自旋翻转器-金属-超导体（S-N1-sf-N2-S）结这两种不同的设置中，零能级于-芝巴-鲁西诺夫（YSR）束缚态的出现会使表面奇频超导配对成倍增强。另一方面，在没有这些束缚态的情况下，偶频配对会主导表面奇频配对。具体来说，在 S-N1-sf-N2-S 约瑟夫森结中，零能 YSR 边界态的出现会导致 0π 结转变和表面奇频配对占主导地位。值得注意的是，在没有 YSR 约束态的情况下，奇频配对会消失。有趣的是，在这两种设置中，等自旋三重配对都是奇频超导的主要成分，这可能对超导自旋电子学有重要影响。总之，我们的发现可能有助于通过观测表面奇频配对来探测 YSR 约束态的存在，并有助于更好地理解它们之间的关系。

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