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

Impact of strain and electron–phonon coupling on thermoelectric performance of Germanene

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

Physica E-low-dimensional Systems & Nanostructures

Pub Date : 2024-11-27 DOI: 10.1016/j.physe.2024.116150

Neelesh Gupta , Anup Shrivastava , Jost Adam

This manuscript describes the thermoelectric properties of monolayer germanene under the influence of biaxial strain using the combined approach of ab initio and semi-classical Boltzmann transport theory. To achieve excellent precision in the estimation of the thermoelectric behavior of strained germanene, the research delves into the temperature-dependent scattering time, particularly emphasizing the electron–phonon coupling effect. Incorporating both optical and acoustic phonons is always crucial and key for precisely estimating the scattering time, surpassing the limitations of the deformation potential approximation method. By examining the impact of strain on monolayer germanene and accounting for its scattering time, this approach provides a more practical means of gauging the thermoelectric performance of germanene under the presence of bi-axial strain. Moreover, the study extends its analysis to doped germanene with bi-axial strain, employing the rigid band approximation to investigate its thermoelectric performance. The research extensively estimates the transport properties for both intrinsic and extrinsic germanene, utilizing the hybrid functional HSE06. Additionally, the lattice thermal conductivity of germanene is estimated and compared for the strained and unstrained conditions. The analysis of thermal conductivity involves considering the effects of group velocity and phonon scattering time, providing insights into the nature of heat transport in strained germanene systems. Overall, this comprehensive study contributes to a deeper understanding of the thermoelectric properties of germanene under strain and lays the foundations for potential applications in electronic and thermal devices.

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引用次数: 0

Probing the magnitude of Rashba spin–orbit coupling in a double quantum dot system via finite-frequency shot noise

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

Physica E-low-dimensional Systems & Nanostructures

Pub Date : 2024-11-26 DOI: 10.1016/j.physe.2024.116159

Hai-Bin Xue, Xiao-Yan Ma, Bin Chen, Jian-Bin Chen, Li-Li Xing

In the coupled quantum dot (QD) system, the electrical manipulation of spin degree of freedom of electron based on the spin–orbit coupling (SOC) is one of the important research fields for QD-based spintronic devices. Consequently, how to quantitatively extract the magnitude of the SOC of the coupled QD system is an important issue. Here, we study the finite-frequency shot noise of electron transport through a serially coupled double QD system with Rashba SOC. It is demonstrated that the existence of peaks and dips of the finite-frequency shot noise originates from the quantum coherence of the serially coupled double QD system, and the positions of the peaks and dips are determined by the differences between the energy eigenvalues of the coherent singly-occupied eigenstates that forming the off-diagonal elements of the reduced density matrix. In particular, when the degeneracy of the differences between the energy eigenvalues of the coherent singly-occupied eigenstates equals one, the finite-frequency shot noise shows a peak, whereas the degeneracy equals two, the finite-frequency shot noise shows a dip. Moreover, the spin polarization of the electrodes and the QD-electrode coupling strength have almost no influence on the positions of the peaks and dips, but have some influences on the width and values of peaks and dips. Therefore, the magnitude of the Rashba SOC and the spin-conservation hopping strength can be quantitatively determined by the positions of peaks and dips of the finite-frequency shot noise.

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引用次数: 0

Formation of vanadium dioxide nanocrystal arrays via post-growth annealing for stable and energy-efficient switches

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

Physica E-low-dimensional Systems & Nanostructures

Pub Date : 2024-11-26 DOI: 10.1016/j.physe.2024.116165

K.E. Kapoguzov , S.V. Mutilin , N.I. Lysenko , V.N. Kichay , L.V. Yakovkina , B.V. Voloshin , V.A. Seleznev

The abrupt and reversible semiconductor-metal phase transition in vanadium dioxide nanocrystals has attracted considerable attention for potential applications in oxide electronics, including neuromorphic systems. This study presents a systematic investigation of post-growth annealing conditions for the formation of single VO₂ M-phase nanocrystals arrays from VO_x films synthesized by atomic layer deposition. The composition of the initial VO_x films and the annealing parameters were found to significantly affect the morphology, phase composition and electrical properties of the obtained single nanocrystal arrays. Our results demonstrate that the formation of VO₂ M-phase nanocrystal arrays occurs at annealing temperatures of 650 °C and above, irrespective of the initial film composition. More homogeneous in size nanocrystals are formed from initial VO_x films with higher V⁺⁴ content. The structures with the initial V⁺⁴ content of 60 % annealed at 650 °C for 2 h demonstrates the resistive switching with an energy less than 150 fJ, and a total number of stable switching cycles more than 10¹⁰. Our results pave the way for the novel energy-efficient nanoelectronic and nanophotonic devices based on VO₂ nanoparticles.

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引用次数: 0

First-Principles prediction of Janus γ-Ge2STe as a potential multifunctional material for photocatalysts, photovoltaic, and piezoelectric applications 对 Janus γ-Ge2STe 作为光催化剂、光伏和压电应用的潜在多功能材料的第一性原理预测

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

Physica E-low-dimensional Systems & Nanostructures

Pub Date : 2024-11-19 DOI: 10.1016/j.physe.2024.116151

Mengshi Zhou , Zhentao Fu , Jin Li , Chunxiao Zhang , Chaoyu He , Tao Ouyang , Chao Tang , Jianxin Zhong

Two-dimensional Janus nanomaterials have been demonstrated great potentail applications in high-performance multifunctional devices due to their asymmetric structural characteristics. In this study, we propose a monolayer Janus γ-Ge₂STe and have studied its electronic, transport, optical, and piezoelectric properties by first-principles calculations. The results show that the Janus structure γ-Ge₂STe is an indirect bandgap semiconductor with intrinsic 'Mexican hat' energy band dispersion pattern and possesses excellent optical performance with high absorbance and photocurrent. Due to the intrinsic electric dipole and suitable band edges, γ-Ge₂STe exhibits strong solar hydrogen production efficiency (η_STH = 20.39 %), which can also be enhanced to 24.48 % by the in-plane tensile strain effectively. Remarkably, owing to the breaking of inversion symmetry, γ-Ge₂STe reveals a strong piezoelectric response (d₁₁ = 14.02 pm/V) under the piezoelectric stress-strain coefficient. The diverse characteristics of monolayer Janus γ-Ge₂STe, coupled with its overall stability (thermal, dynamic, and mechanical), highlight its potential multifunctional applications in catalysts, nanoelectronics, photovoltaics, and piezoelectrics.

二维 Janus 纳米材料因其不对称的结构特征而在高性能多功能器件中展现出巨大的应用潜力。在本研究中，我们提出了一种单层 Janus γ-Ge2STe，并通过第一性原理计算研究了其电子、输运、光学和压电特性。结果表明，Janus 结构的 γ-Ge2STe 是一种间接带隙半导体，具有固有的 "墨西哥帽 "能带色散模式，并具有优异的光学性能，具有很高的吸光度和光电流。由于本征电偶极子和合适的能带边缘，γ-Ge2STe 具有很高的太阳能制氢效率（ηSTH = 20.39 %），通过面内拉伸应变还能有效地将制氢效率提高到 24.48 %。值得注意的是，由于反转对称性被打破，γ-Ge2STe 在压电应力应变系数下显示出很强的压电响应（d11 = 14.02 pm/V）。单层 Janus γ-Ge2STe 的各种特性，加上其整体稳定性（热、动态和机械），突显了其在催化剂、纳米电子学、光伏和压电等领域的多功能应用潜力。

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引用次数: 0

Resonant spin dynamics of 2D electrons with strong Rashba and Zeeman couplings 具有强拉什巴和泽曼耦合的二维电子共振自旋动力学

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.2024.116147

M.A. Rakitskii , K.S. Denisov , I.V. Rozhansky , N.S. Averkiev

Two-dimensional (2D) systems enable enhancing and diversifying the spin–orbit coupling of carriers, a key factor for better charge–spin conversion efficiencies in modern spintronic devices. Increasing 2D spin interactions also modifies dynamical spin-dependent properties of 2D materials, enabling to display resonant phenomena. In this work we focus on dynamical properties of the charge–spin conversion and analyze the resonant spin dynamics of 2D electrons upon strong spin–orbit coupling and Zeeman spin splittings, possibly exceeding the inverse relaxation times of electrons. We derive resonant frequencies and relaxation rates from the Bloch kinetic equations and examine how the trajectories of spin susceptibility poles change with variations in spin splittings and the relaxation time, paying special attention to the interplay between competing Rashba and Zeeman effect.

二维（2D）系统能够增强载流子的自旋轨道耦合并使之多样化，这是提高现代自旋电子器件电荷-自旋转换效率的关键因素。增加二维自旋相互作用还能改变二维材料的动态自旋相关特性，从而显示共振现象。在这项研究中，我们将重点放在电荷-自旋转换的动力学特性上，分析二维电子在强自旋轨道耦合和泽曼自旋分裂时的共振自旋动力学，这可能会超过电子的逆弛豫时间。我们从布洛赫动力学方程中推导出共振频率和弛豫速率，并研究了自旋感性极点的轨迹如何随着自旋分裂和弛豫时间的变化而变化，特别关注了相互竞争的拉什巴效应和泽曼效应之间的相互作用。

引用次数: 0

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