The electrical characteristics of a carbon nanotube can be significantly modified by applying elastic strain. This study focuses on exploring this phenomenon in a single-walled carbon nanotube (SWNT) using tight-binding transport calculations. The results indicate that, under specific strains, an armchair SWNT can act as a filter, separating the two valley electrons K and Kp. Notably, when subjected to deformation, the SWNT exhibits intriguing behaviors, including a quantized conductance profile that varies with the strength of the strain. Consequently, precise control of the width of the quantized plateaus allows for the generation of a polarized valley current. Furthermore, when both K-types are conducted, the strain is demonstrated to completely separate them, directing each K-type through a distinct pathway.
碳纳米管的电气特性可通过施加弹性应变而显著改变。本研究利用紧密结合传输计算，重点探讨了单壁碳纳米管（SWNT）中的这一现象。结果表明，在特定的应变下，臂向 SWNT 可以充当过滤器，将两个谷电子 K 和 Kp 分离开来。值得注意的是，当发生形变时，SWNT 会表现出耐人寻味的行为，包括随应变强度变化的量化电导曲线。因此，精确控制量子化高原的宽度就能产生极化谷电流。此外，当两种 K 型同时传导时，应变能完全将它们分开，引导每种 K 型通过不同的途径。
{"title":"Carbon nanotube as quantum point contact valley-filter and valley-splitter","authors":"Naif Hadadi, Adel Belayadi, Ousmane Ly, Adel Abbout","doi":"arxiv-2409.04815","DOIUrl":"https://doi.org/arxiv-2409.04815","url":null,"abstract":"The electrical characteristics of a carbon nanotube can be significantly\u0000modified by applying elastic strain. This study focuses on exploring this\u0000phenomenon in a single-walled carbon nanotube (SWNT) using tight-binding\u0000transport calculations. The results indicate that, under specific strains, an\u0000armchair SWNT can act as a filter, separating the two valley electrons K and\u0000Kp. Notably, when subjected to deformation, the SWNT exhibits intriguing\u0000behaviors, including a quantized conductance profile that varies with the\u0000strength of the strain. Consequently, precise control of the width of the\u0000quantized plateaus allows for the generation of a polarized valley current.\u0000Furthermore, when both K-types are conducted, the strain is demonstrated to\u0000completely separate them, directing each K-type through a distinct pathway.","PeriodicalId":501137,"journal":{"name":"arXiv - PHYS - Mesoscale and Nanoscale Physics","volume":"58 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142206821","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Vishnu Ottapilakkal, Abhishek Juyal, Suresh Sundaram, Phuong Vuong, Collin Beck, Noel L. Dudeck, Amira Bencherif, Annick Loiseau, Frédéric Fossard, Jean-Sebastien Mérot, David Chapron, Thomas H. Kauffmann, Jean-Paul Salvestrini, Paul L. Voss, Walt A. de Heer, Claire Berger, Abdallah Ougazzaden
Hexagonal boron nitride encapsulation is the method of choice for protecting graphene from environmental doping and impurity scattering. It was previously demonstrated that metal-organic vapor phase epitaxy (MOVPE) grows epitaxially ordered, uniform BN layers on epigraphene (graphene grown on SiC). Due to graphene non-wetting properties, h-BN growth starts preferentially from the graphene ledges. We use this fact here to selectively promote growth of high-quality flat h-BN on epigraphene by patterning epigraphene microstructures prior to BN growth. Thin h-BN films (down to 6 nm) grown by MOVPE show smooth and pleated surface morphology on epigraphene, while crumpled BN is observed on the SiC. Cross-sectional high-resolution transmission electron microscopy images and fluorescence imaging confirm the higher BN quality grown on the epigraphene. Transport measurements reveal p-doping as expected from hydrogen intercalation of epigraphene and regions of high and low mobility. This method can be used to produce structurally uniform high-quality h-BN/epigraphene micro/nano scale heterostructure.
{"title":"High-quality hexagonal boron nitride selectively grown on patterned epigraphene by MOVPE","authors":"Vishnu Ottapilakkal, Abhishek Juyal, Suresh Sundaram, Phuong Vuong, Collin Beck, Noel L. Dudeck, Amira Bencherif, Annick Loiseau, Frédéric Fossard, Jean-Sebastien Mérot, David Chapron, Thomas H. Kauffmann, Jean-Paul Salvestrini, Paul L. Voss, Walt A. de Heer, Claire Berger, Abdallah Ougazzaden","doi":"arxiv-2409.04709","DOIUrl":"https://doi.org/arxiv-2409.04709","url":null,"abstract":"Hexagonal boron nitride encapsulation is the method of choice for protecting\u0000graphene from environmental doping and impurity scattering. It was previously\u0000demonstrated that metal-organic vapor phase epitaxy (MOVPE) grows epitaxially\u0000ordered, uniform BN layers on epigraphene (graphene grown on SiC). Due to\u0000graphene non-wetting properties, h-BN growth starts preferentially from the\u0000graphene ledges. We use this fact here to selectively promote growth of\u0000high-quality flat h-BN on epigraphene by patterning epigraphene microstructures\u0000prior to BN growth. Thin h-BN films (down to 6 nm) grown by MOVPE show smooth\u0000and pleated surface morphology on epigraphene, while crumpled BN is observed on\u0000the SiC. Cross-sectional high-resolution transmission electron microscopy\u0000images and fluorescence imaging confirm the higher BN quality grown on the\u0000epigraphene. Transport measurements reveal p-doping as expected from hydrogen\u0000intercalation of epigraphene and regions of high and low mobility. This method\u0000can be used to produce structurally uniform high-quality h-BN/epigraphene\u0000micro/nano scale heterostructure.","PeriodicalId":501137,"journal":{"name":"arXiv - PHYS - Mesoscale and Nanoscale Physics","volume":"3 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142206779","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Two-dimensional (2D) semiconductors have emerged as leading candidates for the development of low-power and multifunctional computing applications, thanks to their qualities such as layer-dependent band gap tunability, high carrier mobility, and excellent electrostatic control. Here, we explore a pair of 2D semiconductors with broken-gap (Type III) band alignment and demonstrate a highly gate-tunable p-MoTe$_{2}$/n-SnS$_{2}$ heterojunction tunnel field-effect transistor with multifunctional behavior. Employing a dual-gated asymmetric device geometry, we unveil its functionality as both a forward and backward rectifying device. Consequently, we observe a highly gate-tunable negative differential resistance (NDR), with a gate-coupling efficiency of $eta simeq 0.5$ and a peak-to-valley ratio of $sim$ 3 down to 150K. By employing density functional theory and exploring the density of states, we determine that interband tunneling within the valence bands is the cause of the observed NDR characteristics. The combination of band-to-band tunneling and gate controllability of NDR signal open the pathway for realizing gate-tunable 2D material-based neuromorphic and energy-efficient electronics.
{"title":"Gate-tunable negative differential resistance in multifunctional van der Waals heterostructure","authors":"Richa Mitra, Konstantina Iordanidou, Naveen Shetty, Md Anamul Hoque, Anushree Datta, Alexei Kalaboukhov, Julia Wiktor, Sergey Kubatkin, Saroj Prasad Dash, Samuel Lara-Avila","doi":"arxiv-2409.04908","DOIUrl":"https://doi.org/arxiv-2409.04908","url":null,"abstract":"Two-dimensional (2D) semiconductors have emerged as leading candidates for\u0000the development of low-power and multifunctional computing applications, thanks\u0000to their qualities such as layer-dependent band gap tunability, high carrier\u0000mobility, and excellent electrostatic control. Here, we explore a pair of 2D\u0000semiconductors with broken-gap (Type III) band alignment and demonstrate a\u0000highly gate-tunable p-MoTe$_{2}$/n-SnS$_{2}$ heterojunction tunnel field-effect\u0000transistor with multifunctional behavior. Employing a dual-gated asymmetric\u0000device geometry, we unveil its functionality as both a forward and backward\u0000rectifying device. Consequently, we observe a highly gate-tunable negative\u0000differential resistance (NDR), with a gate-coupling efficiency of $eta simeq\u00000.5$ and a peak-to-valley ratio of $sim$ 3 down to 150K. By employing density\u0000functional theory and exploring the density of states, we determine that\u0000interband tunneling within the valence bands is the cause of the observed NDR\u0000characteristics. The combination of band-to-band tunneling and gate\u0000controllability of NDR signal open the pathway for realizing gate-tunable 2D\u0000material-based neuromorphic and energy-efficient electronics.","PeriodicalId":501137,"journal":{"name":"arXiv - PHYS - Mesoscale and Nanoscale Physics","volume":"17 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142206774","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Electron optics deals with the wave-nature of charge carriers to induce, investigate and exploit coherent phenomena in solid state devices, in analogy with optics and photonics. Typically, these goals are achieved in complex electronic devices taking advantage of the macroscopically coherent charge transport in two dimensional electron gases and superconductors. Here, we demonstrate a simple counterintuitive architecture employing intentionally-created lattice defects to induce collective coherent effects in the charge transport of graphene. More specifically, multiple Fabry-P'erot cavities are produced by irradiating graphene via low-energy electron-beam to form periodically alternated defective and pristine nano-stripes. The enhanced hole-doping in the defective stripes creates potential barriers behaving as partially reflecting mirrors and resonantly confining the carrier-waves within the pristine areas. The interference effects are both theoretically and experimentally investigated and manifest as sheet resistance oscillations up to 30 K for both polarities of charge carriers, contrarily to traditional electrostatically-created Fabry-P'erot interferometers. Our findings propose defective graphene as an original platform for the realization of innovative coherent electronic devices with applications in nano and quantum technologies.
{"title":"Bipolar Fabry-Pérot charge interferometer in periodically electron-irradiated graphene","authors":"Nicola Melchioni, Federico Paolucci, Paolo Marconcini, Massimo Macucci, Stefano Roddaro, Alessandro Tredicucci, Federica Bianco","doi":"arxiv-2409.04858","DOIUrl":"https://doi.org/arxiv-2409.04858","url":null,"abstract":"Electron optics deals with the wave-nature of charge carriers to induce,\u0000investigate and exploit coherent phenomena in solid state devices, in analogy\u0000with optics and photonics. Typically, these goals are achieved in complex\u0000electronic devices taking advantage of the macroscopically coherent charge\u0000transport in two dimensional electron gases and superconductors. Here, we\u0000demonstrate a simple counterintuitive architecture employing\u0000intentionally-created lattice defects to induce collective coherent effects in\u0000the charge transport of graphene. More specifically, multiple Fabry-P'erot\u0000cavities are produced by irradiating graphene via low-energy electron-beam to\u0000form periodically alternated defective and pristine nano-stripes. The enhanced\u0000hole-doping in the defective stripes creates potential barriers behaving as\u0000partially reflecting mirrors and resonantly confining the carrier-waves within\u0000the pristine areas. The interference effects are both theoretically and\u0000experimentally investigated and manifest as sheet resistance oscillations up to\u000030 K for both polarities of charge carriers, contrarily to traditional\u0000electrostatically-created Fabry-P'erot interferometers. Our findings propose\u0000defective graphene as an original platform for the realization of innovative\u0000coherent electronic devices with applications in nano and quantum technologies.","PeriodicalId":501137,"journal":{"name":"arXiv - PHYS - Mesoscale and Nanoscale Physics","volume":"63 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142226287","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
We develop a theory for long wavelength phonons originating at dislocations separating domains in small-angle twisted homobilayers of 2D materials such as graphene and MX$_2$ transition metal dichalcogenides (M=Mo,W; X=S,Se). We find that both partial and perfect dislocations, forming due to lattice relaxation in the twisted bilayers with parallel and anti-parallel alignment of unit cells of the constituent layers, respectively, support several one-dimensional subbands of the {it interdomain} phonons. We show that spectrum of the lowest gapless subband is characterized by imaginary frequencies, for wave-numbers below a critical value, dependent on the dislocation orientation, which indicates an instability for long enough straight partial and perfect dislocations. The other subbands are gapped, with subband bottoms lying below the frequency of interlayer shear mode in domains, which facilitates their detection with the help of optical and magnetotransport techniques.
{"title":"Long wavelength interdomain phonons and instability of dislocations in small-angle twisted bilayers","authors":"V. V. Enaldiev","doi":"arxiv-2409.04166","DOIUrl":"https://doi.org/arxiv-2409.04166","url":null,"abstract":"We develop a theory for long wavelength phonons originating at dislocations\u0000separating domains in small-angle twisted homobilayers of 2D materials such as\u0000graphene and MX$_2$ transition metal dichalcogenides (M=Mo,W; X=S,Se). We find\u0000that both partial and perfect dislocations, forming due to lattice relaxation\u0000in the twisted bilayers with parallel and anti-parallel alignment of unit cells\u0000of the constituent layers, respectively, support several one-dimensional\u0000subbands of the {it interdomain} phonons. We show that spectrum of the lowest\u0000gapless subband is characterized by imaginary frequencies, for wave-numbers\u0000below a critical value, dependent on the dislocation orientation, which\u0000indicates an instability for long enough straight partial and perfect\u0000dislocations. The other subbands are gapped, with subband bottoms lying below\u0000the frequency of interlayer shear mode in domains, which facilitates their\u0000detection with the help of optical and magnetotransport techniques.","PeriodicalId":501137,"journal":{"name":"arXiv - PHYS - Mesoscale and Nanoscale Physics","volume":"5 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142206827","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Nard Dumoulin Stuyck, Andre Saraiva, Will Gilbert, Jesus Cifuentes Pardo, Ruoyu Li, Christopher C. Escott, Kristiaan De Greve, Sorin Voinigescu, David J. Reilly, Andrew S. Dzurak
Several domains of society will be disrupted once millions of high-quality qubits can be brought together to perform fault-tolerant quantum computing (FTQC). All quantum computing hardware available today is many orders of magnitude removed from the requirements for FTQC. The intimidating challenges associated with integrating such complex systems have already been addressed by the semiconductor industry -hence many qubit makers have retrofitted their technology to be CMOS-compatible. This compatibility, however, can have varying degrees ranging from the mere ability to fabricate qubits using a silicon wafer as a substrate, all the way to the co-integration of qubits with high-yield, low-power advanced electronics to control these qubits. Extrapolating the evolution of quantum processors to future systems, semiconductor spin qubits have unique advantages in this respect, making them one of the most serious contenders for large-scale FTQC. In this review, we focus on the overlap between state-of-the-art semiconductor spin qubit systems and CMOS industry Very Large-Scale Integration (VLSI) principles. We identify the main differences in spin qubit operation, material, and system requirements compared to well-established CMOS industry practices. As key players in the field are looking to collaborate with CMOS industry partners, this review serves to accelerate R&D towards the industrial scale production of FTQC processors.
{"title":"CMOS compatibility of semiconductor spin qubits","authors":"Nard Dumoulin Stuyck, Andre Saraiva, Will Gilbert, Jesus Cifuentes Pardo, Ruoyu Li, Christopher C. Escott, Kristiaan De Greve, Sorin Voinigescu, David J. Reilly, Andrew S. Dzurak","doi":"arxiv-2409.03993","DOIUrl":"https://doi.org/arxiv-2409.03993","url":null,"abstract":"Several domains of society will be disrupted once millions of high-quality\u0000qubits can be brought together to perform fault-tolerant quantum computing\u0000(FTQC). All quantum computing hardware available today is many orders of\u0000magnitude removed from the requirements for FTQC. The intimidating challenges\u0000associated with integrating such complex systems have already been addressed by\u0000the semiconductor industry -hence many qubit makers have retrofitted their\u0000technology to be CMOS-compatible. This compatibility, however, can have varying\u0000degrees ranging from the mere ability to fabricate qubits using a silicon wafer\u0000as a substrate, all the way to the co-integration of qubits with high-yield,\u0000low-power advanced electronics to control these qubits. Extrapolating the\u0000evolution of quantum processors to future systems, semiconductor spin qubits\u0000have unique advantages in this respect, making them one of the most serious\u0000contenders for large-scale FTQC. In this review, we focus on the overlap\u0000between state-of-the-art semiconductor spin qubit systems and CMOS industry\u0000Very Large-Scale Integration (VLSI) principles. We identify the main\u0000differences in spin qubit operation, material, and system requirements compared\u0000to well-established CMOS industry practices. As key players in the field are\u0000looking to collaborate with CMOS industry partners, this review serves to\u0000accelerate R&D towards the industrial scale production of FTQC processors.","PeriodicalId":501137,"journal":{"name":"arXiv - PHYS - Mesoscale and Nanoscale Physics","volume":"71 1 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142206829","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Using spectral energy density method, we predict the phonon scattering mean lifetimes of polycrystalline graphene (PC-G) having polycrystallinity only along $rm{x}$-axis with seven different misorientation (tilt) angles at room temperature. Contrary to other studies on PC-G samples, our results indicate strong dependence of the thermal conductivity (TC) on the tilt angles. We also show that the square of the group velocity components along $rm{x}$ and $rm{y}$ axes and the phonon lifetimes are uncorrelated and the phonon density of states are almost the same for all samples with different tilt angles. Further, a distribution of the group velocity component along $rm{x}$ or $rm{y}$ axis as function of normal frequency is found to be exponentially decaying whereas that of phonon lifetime showed piecewise constant function behavior with respect to frequency. We provide parameters for these distribution functions and suggest another measure of the TC based on these distributions. Finally, we perform a size-dependent analysis for two tilt angles, $21.78^circ$ and $32.20^circ$, and find that bulk TC components decrease by around 34% to 62% in comparison to the bulk TC values of the pristine graphene. Our analysis reveals intriguing insights into the interplay between grain orientation, phonon scattering and thermal conductivity in graphene.
{"title":"Lattice thermal conductivity and phonon properties of polycrystalline graphene","authors":"Kunwar Abhikeern, Amit Singh","doi":"arxiv-2409.04503","DOIUrl":"https://doi.org/arxiv-2409.04503","url":null,"abstract":"Using spectral energy density method, we predict the phonon scattering mean\u0000lifetimes of polycrystalline graphene (PC-G) having polycrystallinity only\u0000along $rm{x}$-axis with seven different misorientation (tilt) angles at room\u0000temperature. Contrary to other studies on PC-G samples, our results indicate\u0000strong dependence of the thermal conductivity (TC) on the tilt angles. We also\u0000show that the square of the group velocity components along $rm{x}$ and\u0000$rm{y}$ axes and the phonon lifetimes are uncorrelated and the phonon density\u0000of states are almost the same for all samples with different tilt angles.\u0000Further, a distribution of the group velocity component along $rm{x}$ or\u0000$rm{y}$ axis as function of normal frequency is found to be exponentially\u0000decaying whereas that of phonon lifetime showed piecewise constant function\u0000behavior with respect to frequency. We provide parameters for these\u0000distribution functions and suggest another measure of the TC based on these\u0000distributions. Finally, we perform a size-dependent analysis for two tilt\u0000angles, $21.78^circ$ and $32.20^circ$, and find that bulk TC components\u0000decrease by around 34% to 62% in comparison to the bulk TC values of the\u0000pristine graphene. Our analysis reveals intriguing insights into the interplay\u0000between grain orientation, phonon scattering and thermal conductivity in\u0000graphene.","PeriodicalId":501137,"journal":{"name":"arXiv - PHYS - Mesoscale and Nanoscale Physics","volume":"75 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142206823","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Maarten Stroeks, Daan Lenterman, Barbara Terhal, Yaroslav Herasymenko
The simulation of time-dynamics and thermal states of free fermions on N = 2^n modes are known to require poly(2^n) computational classical resources. We present several such free fermion problems that can be solved by a quantum algorithm with exponentially-improved, poly(n) cost. The key technique is the block-encoding of the correlation matrix into a unitary. We demonstrate how such a unitary can be efficiently realized as a quantum circuit, in the context of dynamics and thermal states of tight-binding Hamiltonians. We prove that the problem of free fermion time-dynamics is BQP-complete, thus ensuring a general exponential speedup of our approach.
众所周知，模拟自由费米子在 N =2^n 模式上的时间动力学和热状态需要 poly(2^n) 计算经典资源。我们提出了几个这样的自由费米子问题，它们可以通过量子算法以指数级改进的poly(n)成本来解决。其中的关键技术是将相关矩阵阻塞编码成单元。我们演示了如何在紧密结合哈密顿的动力学和热态背景下，将这种单元有效地实现为量子电路。我们证明了自由费米子时间动力学问题是 BQP 完备的，从而确保了我们方法的泛指数加速。
{"title":"Solving Free Fermion Problems on a Quantum Computer","authors":"Maarten Stroeks, Daan Lenterman, Barbara Terhal, Yaroslav Herasymenko","doi":"arxiv-2409.04550","DOIUrl":"https://doi.org/arxiv-2409.04550","url":null,"abstract":"The simulation of time-dynamics and thermal states of free fermions on N =\u00002^n modes are known to require poly(2^n) computational classical resources. We\u0000present several such free fermion problems that can be solved by a quantum\u0000algorithm with exponentially-improved, poly(n) cost. The key technique is the\u0000block-encoding of the correlation matrix into a unitary. We demonstrate how\u0000such a unitary can be efficiently realized as a quantum circuit, in the context\u0000of dynamics and thermal states of tight-binding Hamiltonians. We prove that the\u0000problem of free fermion time-dynamics is BQP-complete, thus ensuring a general\u0000exponential speedup of our approach.","PeriodicalId":501137,"journal":{"name":"arXiv - PHYS - Mesoscale and Nanoscale Physics","volume":"7 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142226288","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Sara Bey, Shelby S. Fields, Nicholas G. Combs, Bence G. Márkus, Dávid Beke, Jiashu Wang, Anton V. Ievlev, Maksym Zhukovskyi, Tatyana Orlova, László Forró, Steven P. Bennett, Xinyu Liu, Badih A. Assaf
The discovery of an anomalous Hall effect (AHE) sensitive to the magnetic state of antiferromagnets can trigger a new era of spintronics, if materials that host a tunable and strong AHE are identified. Altermagnets are a new class of materials that can under certain conditions manifest a strong AHE, without having a net magnetization. But the ability to control their AHE is still lacking. In this study, we demonstrate that the AHE in altermagnetic {alpha}-MnTe grown on GaAs(111) substrates can be "written on-demand" by cooling the material under an in-plane magnetic field. The magnetic field controls the strength and the coercivity of the AHE. Remarkably, this control is unique to {alpha}-MnTe grown on GaAs and is absent in {alpha}-MnTe grown on SrF2. The tunability that we reveal challenges our current understanding of the symmetry-allowed AHE in this material and opens new possibilities for the design of altermagnetic spintronic devices.
{"title":"Unexpected Tuning of the Anomalous Hall Effect in Altermagnetic MnTe Thin Films","authors":"Sara Bey, Shelby S. Fields, Nicholas G. Combs, Bence G. Márkus, Dávid Beke, Jiashu Wang, Anton V. Ievlev, Maksym Zhukovskyi, Tatyana Orlova, László Forró, Steven P. Bennett, Xinyu Liu, Badih A. Assaf","doi":"arxiv-2409.04567","DOIUrl":"https://doi.org/arxiv-2409.04567","url":null,"abstract":"The discovery of an anomalous Hall effect (AHE) sensitive to the magnetic\u0000state of antiferromagnets can trigger a new era of spintronics, if materials\u0000that host a tunable and strong AHE are identified. Altermagnets are a new class\u0000of materials that can under certain conditions manifest a strong AHE, without\u0000having a net magnetization. But the ability to control their AHE is still\u0000lacking. In this study, we demonstrate that the AHE in altermagnetic\u0000{alpha}-MnTe grown on GaAs(111) substrates can be \"written on-demand\" by\u0000cooling the material under an in-plane magnetic field. The magnetic field\u0000controls the strength and the coercivity of the AHE. Remarkably, this control\u0000is unique to {alpha}-MnTe grown on GaAs and is absent in {alpha}-MnTe grown\u0000on SrF2. The tunability that we reveal challenges our current understanding of\u0000the symmetry-allowed AHE in this material and opens new possibilities for the\u0000design of altermagnetic spintronic devices.","PeriodicalId":501137,"journal":{"name":"arXiv - PHYS - Mesoscale and Nanoscale Physics","volume":"45 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142206820","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Marc Rovirola, M. Waqas Khaliq, Blai Casals, Adrian Begué, Neven Biskup, Noelia Coton, Joan Manel Hernàndez, Miguel Angel Niño, Michael Foerster, Alberto Hernández-Mínguez, Rocío Ranchal, Marius V. Costache, Antoni García-Santiago, Ferran Macià
The interaction between surface acoustic waves and magnetization offers an efficient route for electrically controlling magnetic states. Here, we demonstrate the excitation of magnetoacoustic waves in galfenol, a highly magnetostrictive alloy made of iron (72%) and gallium (28%). We quantify the amplitude of the induced magnetization oscillations using magnetic imaging in an X-ray photoelectron microscope and estimate the dynamic magnetoelastic constants through micromagnetic simulations. Our findings demonstrate the potential of galfenol for magnonic applications and reveal that, despite strong magnetoelastic coupling, magnetic interactions and spin-wave dispersion relations significantly influence the overall amplitude of magnetoacoustic waves.
表面声波与磁化之间的相互作用为电控磁态提供了一条有效途径。在这里，我们展示了在一种由铁（72%）和镓（28%）制成的高磁致伸缩性合金--galfenol 中激发磁声波的过程。我们利用 X 射线光电子显微镜的磁成像技术量化了诱导磁化振荡的振幅，并通过微磁模拟估算了动态磁弹性常数。我们的研究结果证明了镓酚在磁性应用方面的潜力，并揭示了尽管磁弹性耦合很强，但磁相互作用和自旋波色散关系对磁声波的整体振幅有很大影响。
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