Neuromorphic spintronics combines two advanced fields in technology, neuromorphic computing and spintronics, to create brain-inspired, efficient computing systems that leverage the unique properties of the electron's spin. In this book chapter, we first introduce both fields - neuromorphic computing and spintronics and then make a case for neuromorphic spintronics. We discuss concrete examples of neuromorphic spintronics, including computing based on fluctuations, artificial neural networks, and reservoir computing, highlighting their potential to revolutionize computational efficiency and functionality.
{"title":"Neuromorphic Spintronics","authors":"Atreya Majumdar, Karin Everschor-Sitte","doi":"arxiv-2409.10290","DOIUrl":"https://doi.org/arxiv-2409.10290","url":null,"abstract":"Neuromorphic spintronics combines two advanced fields in technology,\u0000neuromorphic computing and spintronics, to create brain-inspired, efficient\u0000computing systems that leverage the unique properties of the electron's spin.\u0000In this book chapter, we first introduce both fields - neuromorphic computing\u0000and spintronics and then make a case for neuromorphic spintronics. We discuss\u0000concrete examples of neuromorphic spintronics, including computing based on\u0000fluctuations, artificial neural networks, and reservoir computing, highlighting\u0000their potential to revolutionize computational efficiency and functionality.","PeriodicalId":501211,"journal":{"name":"arXiv - PHYS - Other Condensed Matter","volume":"55 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142252606","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 numerically examine the corotation of two parallel quantized vortices in a self-gravitating Bose-Einstein condensate (BEC) employing the Gross-Pitaevskii-Poisson equations. The long-range gravitationally attractive interaction allows the BEC to self-confine without the need for external potentials, while the density-dependence of the gravitational potential induces intriguing behaviors in the quantized vortices. The aim of this study is to provide a clue for understanding the corotation of two quantized vortices under the influence of gravitational interactions. The corotation of two quantized vortices is coupled with collective modes of the BEC, which markedly differs from the behavior observed in typical BECs confined by an external potential. The rotational period increases linearly with the initial position from the center of the BEC. This deviation from the quadratic increase observed in a uniform BEC suggests that the gravitational interaction exerts a drag effect on the rotating quantized vortices. The two closely positioned quantized vortices rotate along elliptical orbits with radial fluctuations. However, when the quantized vortices are initially positioned beyond a critical radius comparable to their core sizes, their trajectory transitions into an outward spiral, implying the onset of effective dissipation. Our findings demonstrate that the radial fluctuations of the quantized vortex resonate with the quadrupole mode of the BEC, giving rise to a dissipation mechanism.
{"title":"Corotation of two quantized vortices coupled with collective modes in self-gravitating Bose-Einstein condensates","authors":"Kenta Asakawa, Makoto Tsubota","doi":"arxiv-2409.07860","DOIUrl":"https://doi.org/arxiv-2409.07860","url":null,"abstract":"We numerically examine the corotation of two parallel quantized vortices in a\u0000self-gravitating Bose-Einstein condensate (BEC) employing the\u0000Gross-Pitaevskii-Poisson equations. The long-range gravitationally attractive\u0000interaction allows the BEC to self-confine without the need for external\u0000potentials, while the density-dependence of the gravitational potential induces\u0000intriguing behaviors in the quantized vortices. The aim of this study is to\u0000provide a clue for understanding the corotation of two quantized vortices under\u0000the influence of gravitational interactions. The corotation of two quantized\u0000vortices is coupled with collective modes of the BEC, which markedly differs\u0000from the behavior observed in typical BECs confined by an external potential.\u0000The rotational period increases linearly with the initial position from the\u0000center of the BEC. This deviation from the quadratic increase observed in a\u0000uniform BEC suggests that the gravitational interaction exerts a drag effect on\u0000the rotating quantized vortices. The two closely positioned quantized vortices\u0000rotate along elliptical orbits with radial fluctuations. However, when the\u0000quantized vortices are initially positioned beyond a critical radius comparable\u0000to their core sizes, their trajectory transitions into an outward spiral,\u0000implying the onset of effective dissipation. Our findings demonstrate that the\u0000radial fluctuations of the quantized vortex resonate with the quadrupole mode\u0000of the BEC, giving rise to a dissipation mechanism.","PeriodicalId":501211,"journal":{"name":"arXiv - PHYS - Other Condensed Matter","volume":"32 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142181820","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}
Christelle Inès K. Mebou, Martin E. Garcia, Tobias Zier
Highly non-equilibrium conditions in femtosecond-laser excited solids cause a variety of ultrafast phenomena that are not accessible by thermal conditions, like sub-picosecond solid-to-liquid or solid-to-solid phase transitions. In recent years the microscopic pathways of various laser-induced crystal rearrangements could be identified and led to novel applications and/or improvements in optoelectronics, photonics, and nanotechnology. However, it remains unclear what effect a femtosecond-laser excitation has on ionic impurities within an altered crystal environment, in particular on the atomic mobility. Here, we performed ab-initio molecular dynamics (AIMD) simulations on laser-excited black silicon, a promising material for high-efficient solar cells, using the Code for Highly excIted Valence Electron Systems (CHIVES). By computing time-dependent Bragg peak intensities for doping densities of 0.16% and 2.31% we could identify the overall weakening of the crystal environment with increasing impurity density. The analysis of Si-S bond angles and lengths after different excitation densities, as well as computing interatomic forces allowed to identify a change in ion mobility with increasing impurity density and excitation strength. Our results indicate the importance of impurity concentrations for ionic mobility in laser-excited black silicon and could give significant insight for semiconductor device optimization and materials science advancement.
{"title":"Tuned ionic mobility by Ultrafast-laser pulses in Black Silicon","authors":"Christelle Inès K. Mebou, Martin E. Garcia, Tobias Zier","doi":"arxiv-2409.07659","DOIUrl":"https://doi.org/arxiv-2409.07659","url":null,"abstract":"Highly non-equilibrium conditions in femtosecond-laser excited solids cause a\u0000variety of ultrafast phenomena that are not accessible by thermal conditions,\u0000like sub-picosecond solid-to-liquid or solid-to-solid phase transitions. In\u0000recent years the microscopic pathways of various laser-induced crystal\u0000rearrangements could be identified and led to novel applications and/or\u0000improvements in optoelectronics, photonics, and nanotechnology. However, it\u0000remains unclear what effect a femtosecond-laser excitation has on ionic\u0000impurities within an altered crystal environment, in particular on the atomic\u0000mobility. Here, we performed ab-initio molecular dynamics (AIMD) simulations on\u0000laser-excited black silicon, a promising material for high-efficient solar\u0000cells, using the Code for Highly excIted Valence Electron Systems (CHIVES). By\u0000computing time-dependent Bragg peak intensities for doping densities of 0.16%\u0000and 2.31% we could identify the overall weakening of the crystal environment\u0000with increasing impurity density. The analysis of Si-S bond angles and lengths\u0000after different excitation densities, as well as computing interatomic forces\u0000allowed to identify a change in ion mobility with increasing impurity density\u0000and excitation strength. Our results indicate the importance of impurity\u0000concentrations for ionic mobility in laser-excited black silicon and could give\u0000significant insight for semiconductor device optimization and materials science\u0000advancement.","PeriodicalId":501211,"journal":{"name":"arXiv - PHYS - Other Condensed Matter","volume":"32 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142181821","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}
Expanding the performance of field effect devices is a key challenge of the ever-growing chip industry at the core of current technologies. A highly desired nonvolatile response in tiny multiferroic transistors is expected by electric field control of atomic movements rather than the typical electronic redistribution. Recently, such field effect control of structural transitions was established in commensurate stacking configurations of honeycomb van der Waals (vdW) polytypes by sliding narrow boundary dislocations between oppositely polarized domains. The interfacial ferroelectric response, however, relied on preexisting boundary strips between relatively large micron-scale domains, severely limiting practical implementations. Here, we report the robust switching of single-domain polytypes in nm-scale islands embedded in super lubricant vdW arrays. We etch cavities into a thin layered spacer and then encapsulate it with parallel functional flakes. The incommensurate flakes above and under the spacer sag and touch at each cavity to form uniform crystalline islands free from interlayer deformations. By imaging the polytypes' ferroelectric response, we observe reversible nucleation and annihilation of boundary strips and geometry-adaptable hysteresis loops. Using mechanical stress, we accurately position the boundary strip, modify the interlayer twist angle, and nucleate intermediate polar domain patterns. By precisely designing the size, shape, symmetry, and distribution of the islands in these Super Lubricant Arrays of Polytype (SLAP), we envision numerous device functionalities and SlideTronics applications. These range from ultra-sensitive detectors of atomic-scale shifts to nonvolatile multi-ferroic tunneling transistors with tunable coercive switching fields, and even elastically-coupled memory cells for neuromorphic architectures.
{"title":"Switchable Crystalline Islands in Super Lubricant Arrays","authors":"Youngki Yeo, Yoav Sharaby, Nirmal Roy, Noam Raab, Watanabe Kenji, Takashi Taniguchi, Moshe Ben Shalom","doi":"arxiv-2409.07225","DOIUrl":"https://doi.org/arxiv-2409.07225","url":null,"abstract":"Expanding the performance of field effect devices is a key challenge of the\u0000ever-growing chip industry at the core of current technologies. A highly\u0000desired nonvolatile response in tiny multiferroic transistors is expected by\u0000electric field control of atomic movements rather than the typical electronic\u0000redistribution. Recently, such field effect control of structural transitions\u0000was established in commensurate stacking configurations of honeycomb van der\u0000Waals (vdW) polytypes by sliding narrow boundary dislocations between\u0000oppositely polarized domains. The interfacial ferroelectric response, however,\u0000relied on preexisting boundary strips between relatively large micron-scale\u0000domains, severely limiting practical implementations. Here, we report the\u0000robust switching of single-domain polytypes in nm-scale islands embedded in\u0000super lubricant vdW arrays. We etch cavities into a thin layered spacer and\u0000then encapsulate it with parallel functional flakes. The incommensurate flakes\u0000above and under the spacer sag and touch at each cavity to form uniform\u0000crystalline islands free from interlayer deformations. By imaging the\u0000polytypes' ferroelectric response, we observe reversible nucleation and\u0000annihilation of boundary strips and geometry-adaptable hysteresis loops. Using\u0000mechanical stress, we accurately position the boundary strip, modify the\u0000interlayer twist angle, and nucleate intermediate polar domain patterns. By\u0000precisely designing the size, shape, symmetry, and distribution of the islands\u0000in these Super Lubricant Arrays of Polytype (SLAP), we envision numerous device\u0000functionalities and SlideTronics applications. These range from ultra-sensitive\u0000detectors of atomic-scale shifts to nonvolatile multi-ferroic tunneling\u0000transistors with tunable coercive switching fields, and even\u0000elastically-coupled memory cells for neuromorphic architectures.","PeriodicalId":501211,"journal":{"name":"arXiv - PHYS - Other Condensed Matter","volume":"50 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142181823","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}
Airships, best recognized for their unique quality of payload/energy ratio, present a fascinating challenge for the field of engineering. Their construction and operation require a delicate balance of materials and rules, making them a compelling object of study. They embody a distinct intersection of physics, design, and innovation, offering a wide array of possibilities for future transportation and exploration. Thanks to their long-flight endurance, they are suited for long-term missions. To operate in complex environments such as indoor cluttered spaces, their membrane and mechatronics need to be protected from impacts. This paper presents a new indoor airship design inspired by origami and the Kresling pattern. The airship structure combines a carbon fiber exoskeleton and UV resin micro-lattices for shock absorption. Our design strengthens the robot while granting the ability to access narrow spaces by folding the structure - up to a volume expansion ratio of 19.8. To optimize the numerous parameters of the airship, we present a pipeline for design, manufacture, and assembly. It takes into account manufacturing constraints, dimensions of the target deployment area, and aerostatics, allowing for easy and quick testing of new configurations. We also present unique features made possible by combining origami with airship design, which reduces the chances of mission-compromising failures. We demonstrate the potential of the design with a complete simulation including an effective control strategy leveraging lightweight mechatronics to optimize flight autonomy in exploration missions of unstructured environments.
{"title":"CAVERNAUTE: a design and manufacturing pipeline of a rigid but foldable indoor airship aerial system for cave exploration","authors":"Catar Louis, Tabiai Ilyass, St-Onge David","doi":"arxiv-2409.07591","DOIUrl":"https://doi.org/arxiv-2409.07591","url":null,"abstract":"Airships, best recognized for their unique quality of payload/energy ratio,\u0000present a fascinating challenge for the field of engineering. Their\u0000construction and operation require a delicate balance of materials and rules,\u0000making them a compelling object of study. They embody a distinct intersection\u0000of physics, design, and innovation, offering a wide array of possibilities for\u0000future transportation and exploration. Thanks to their long-flight endurance,\u0000they are suited for long-term missions. To operate in complex environments such\u0000as indoor cluttered spaces, their membrane and mechatronics need to be\u0000protected from impacts. This paper presents a new indoor airship design\u0000inspired by origami and the Kresling pattern. The airship structure combines a\u0000carbon fiber exoskeleton and UV resin micro-lattices for shock absorption. Our\u0000design strengthens the robot while granting the ability to access narrow spaces\u0000by folding the structure - up to a volume expansion ratio of 19.8. To optimize\u0000the numerous parameters of the airship, we present a pipeline for design,\u0000manufacture, and assembly. It takes into account manufacturing constraints,\u0000dimensions of the target deployment area, and aerostatics, allowing for easy\u0000and quick testing of new configurations. We also present unique features made\u0000possible by combining origami with airship design, which reduces the chances of\u0000mission-compromising failures. We demonstrate the potential of the design with\u0000a complete simulation including an effective control strategy leveraging\u0000lightweight mechatronics to optimize flight autonomy in exploration missions of\u0000unstructured environments.","PeriodicalId":501211,"journal":{"name":"arXiv - PHYS - Other Condensed Matter","volume":"54 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142181822","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}
In the Fermi liquid metallic state, a static local magnetic moment is induced on the application of a circularly polarized electromagnetic wave, via the inverse Fara-day effect (IFE). The direction of this moment is along the direction of propagation of light, and the magnitude of the moment depends on the frequency of light, the temperature and various material parameters characteristic of the metal. I propose an analogous effect in the Fermi liquid state of $^3$H. A static circulating current is induced when liquid $^3$H is driven by a circularly polarized transverse acoustic wave. For liquid $^3$H filled into aerogel, the coupled system supports a low-attenuation transverse sound mode. I estimate the magnitude of induced circulating currents for this system and find that these are within the range of experimental measurement in the low-attenuation regime. The axis of circulation is along the direction of propagation of the acoustic wave. I propose this analogue of the inverse Faraday effect as a scheme to experimentally demonstrate the propagation of transverse sound in $^3$H-aerogel.
{"title":"Proposal to Observe Transverse Sound in Normal Liquid $^3$He in Aerogel","authors":"Priya Sharma","doi":"arxiv-2409.06363","DOIUrl":"https://doi.org/arxiv-2409.06363","url":null,"abstract":"In the Fermi liquid metallic state, a static local magnetic moment is induced\u0000on the application of a circularly polarized electromagnetic wave, via the\u0000inverse Fara-day effect (IFE). The direction of this moment is along the\u0000direction of propagation of light, and the magnitude of the moment depends on\u0000the frequency of light, the temperature and various material parameters\u0000characteristic of the metal. I propose an analogous effect in the Fermi liquid\u0000state of $^3$H. A static circulating current is induced when liquid $^3$H is\u0000driven by a circularly polarized transverse acoustic wave. For liquid $^3$H\u0000filled into aerogel, the coupled system supports a low-attenuation transverse\u0000sound mode. I estimate the magnitude of induced circulating currents for this\u0000system and find that these are within the range of experimental measurement in\u0000the low-attenuation regime. The axis of circulation is along the direction of\u0000propagation of the acoustic wave. I propose this analogue of the inverse\u0000Faraday effect as a scheme to experimentally demonstrate the propagation of\u0000transverse sound in $^3$H-aerogel.","PeriodicalId":501211,"journal":{"name":"arXiv - PHYS - Other Condensed Matter","volume":"59 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142181824","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}
The recently synthesized 30$^circ$ twisted bilayer graphene (30$^circ$-TBG) systems are unique quasicrystal systems possessing dodecagonal symmetry with graphene's relativistic properties. We employ a real-space numerical atomistic framework that respects both the dodecagonal rotational symmetry and the massless Dirac nature of the electrons to describe the local density of states of the system. The approach we employ is very efficiency for systems with very large unit cells and does not rely on periodic boundary conditions. These features allow us to address a broad class of multilayer two-dimensional crystal with incommensurate configurations, particularly TBGs. Our results reveal that the 30$^circ$-TBG electronic spectrum consist of extended states together with a set of localized wave functions. The localized states exhibit fractal patterns consistent with the quasicrystal tiling.
{"title":"Quasicrystalline 30$^{circ}$ twisted bilayer graphene: Fractal patterns and electronic localization properties","authors":"Kevin J. U. Vidarte, Caio Lewenkopf","doi":"arxiv-2409.05126","DOIUrl":"https://doi.org/arxiv-2409.05126","url":null,"abstract":"The recently synthesized 30$^circ$ twisted bilayer graphene (30$^circ$-TBG)\u0000systems are unique quasicrystal systems possessing dodecagonal symmetry with\u0000graphene's relativistic properties. We employ a real-space numerical atomistic framework that respects both the\u0000dodecagonal rotational symmetry and the massless Dirac nature of the electrons\u0000to describe the local density of states of the system. The approach we employ is very efficiency for systems with very large unit\u0000cells and does not rely on periodic boundary conditions. These features allow\u0000us to address a broad class of multilayer two-dimensional crystal with\u0000incommensurate configurations, particularly TBGs. Our results reveal that the\u000030$^circ$-TBG electronic spectrum consist of extended states together with a\u0000set of localized wave functions. The localized states exhibit fractal patterns\u0000consistent with the quasicrystal tiling.","PeriodicalId":501211,"journal":{"name":"arXiv - PHYS - Other Condensed Matter","volume":"35 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142181825","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}
The Hatano-Nelson (HN) Hamiltonian has played a pivotal role in catalyzing research interest in non-Hermitian systems, primarily because it showcases unique physical phenomena that arise solely due to non-Hermiticity. The non-Hermiticity in the HN Hamiltonian, driven by asymmetric hopping amplitudes, induces a delocalization-localization (DL) transition in a one-dimensional (1D) lattice with random disorder, sharply contrasting with its Hermitian counterpart. A similar DL transition occurs in a 1D quasiperiodic HN (QHN) lattice, where a critical quasiperiodic potential strength separates metallic and insulating states, akin to the Hermitian case. In these systems, all states below the critical potential are delocalized, while those above are localized. In this study, we reveal that coupling two 1D QHN lattices can significantly alter the nature of the DL transition. We identify two critical points, $V_{c1} < V_{c2}$, when the nearest neighbors of the two 1D QHN lattices are cross-coupled with strong hopping amplitudes under periodic boundary conditions (PBC). Generally, all states are completely delocalized below $ V_{c1}$ and completely localized above $V_{c2}$, while two mobility edges symmetrically emerge about $rm{Re[E]} = 0$ between $V_{c1}$ and $V_{c2}$. Notably, under specific asymmetric cross-hopping amplitudes, $V_{c1}$ approaches zero, resulting in localized states even for infinitesimally weak potential. Remarkably, we also find that the mobility edges precisely divide the delocalized and localized states in equal proportions. Furthermore, we observe that the conventional one-to-one correspondence between electronic states under PBC and open boundary conditions (OBC) in 1D HN lattices breaks
{"title":"Engineering unique localization transition with coupled Hatano-Nelson chains","authors":"Ritaban Samanta, Aditi Chakrabarty, Sanjoy Datta","doi":"arxiv-2409.04417","DOIUrl":"https://doi.org/arxiv-2409.04417","url":null,"abstract":"The Hatano-Nelson (HN) Hamiltonian has played a pivotal role in catalyzing\u0000research interest in non-Hermitian systems, primarily because it showcases\u0000unique physical phenomena that arise solely due to non-Hermiticity. The\u0000non-Hermiticity in the HN Hamiltonian, driven by asymmetric hopping amplitudes,\u0000induces a delocalization-localization (DL) transition in a one-dimensional (1D)\u0000lattice with random disorder, sharply contrasting with its Hermitian\u0000counterpart. A similar DL transition occurs in a 1D quasiperiodic HN (QHN)\u0000lattice, where a critical quasiperiodic potential strength separates metallic\u0000and insulating states, akin to the Hermitian case. In these systems, all states\u0000below the critical potential are delocalized, while those above are localized.\u0000In this study, we reveal that coupling two 1D QHN lattices can significantly\u0000alter the nature of the DL transition. We identify two critical points, $V_{c1}\u0000< V_{c2}$, when the nearest neighbors of the two 1D QHN lattices are\u0000cross-coupled with strong hopping amplitudes under periodic boundary conditions\u0000(PBC). Generally, all states are completely delocalized below $ V_{c1}$ and\u0000completely localized above $V_{c2}$, while two mobility edges symmetrically\u0000emerge about $rm{Re[E]} = 0$ between $V_{c1}$ and $V_{c2}$. Notably, under\u0000specific asymmetric cross-hopping amplitudes, $V_{c1}$ approaches zero,\u0000resulting in localized states even for infinitesimally weak potential.\u0000Remarkably, we also find that the mobility edges precisely divide the\u0000delocalized and localized states in equal proportions. Furthermore, we observe\u0000that the conventional one-to-one correspondence between electronic states under\u0000PBC and open boundary conditions (OBC) in 1D HN lattices breaks","PeriodicalId":501211,"journal":{"name":"arXiv - PHYS - Other Condensed Matter","volume":"2 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142181830","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}
Vladislav Nagorkin, Sebastian Schimmel, Paul Gebauer, Anna Isaeva, Danny Baumann, Andreas Koitzsch, Bernd Büchner, Christian Hess
We investigated the electronic properties of the topological insulator Bi$_{2}$Te$_{3}$ by scanning tunneling microscopy and spectroscopy at low temperature. We obtained high-resolution quasiparticle interference data of the topological surface Dirac electrons at different energies. Spin-selective joint density of states calculations were performed for surface and bulk electronic states to interpret the observed quasiparticle interference data. The topological properties of our crystals are demonstrated by the absence of backscattering along with the linear energy dispersion of the dominant scattering vector. In addition, we detect non-dispersive scattering modes which we associate with bulk-surface scattering and, thus, allow an approximate identification of the bulk energy gap range based on our quasiparticle interference data. Measurements of differential conductance maps in magnetic fields up to 15 T have been carried out, but no strong modifications could be observed.
我们在低温下通过扫描隧道显微镜和光谱学研究了拓扑绝缘体Bi$_{2}$Te$_{3}$的电子特性。我们获得了拓扑表面狄拉克电子在不同能量下的高分辨率准粒子干涉数据。为了解释观测到的类粒子干涉数据，我们对表面和体态电子进行了自旋选择性联合态密度计算。我们的晶体不存在反向散射，而且主要散射矢量具有线性能量弥散，这证明了晶体的拓扑特性。此外，我们还探测到了非色散散射模式，并将其与体表散射联系起来，从而可以根据我们的准粒子干涉数据大致确定体表能隙范围。我们还测量了磁场高达 15 T 时的差分电导图，但没有观察到强烈的变化。
{"title":"Bulk and surface electron scattering in disordered Bi$_{2}$Te$_{3}$ probed by quasiparticle interference","authors":"Vladislav Nagorkin, Sebastian Schimmel, Paul Gebauer, Anna Isaeva, Danny Baumann, Andreas Koitzsch, Bernd Büchner, Christian Hess","doi":"arxiv-2409.04294","DOIUrl":"https://doi.org/arxiv-2409.04294","url":null,"abstract":"We investigated the electronic properties of the topological insulator\u0000Bi$_{2}$Te$_{3}$ by scanning tunneling microscopy and spectroscopy at low\u0000temperature. We obtained high-resolution quasiparticle interference data of the\u0000topological surface Dirac electrons at different energies. Spin-selective joint\u0000density of states calculations were performed for surface and bulk electronic\u0000states to interpret the observed quasiparticle interference data. The\u0000topological properties of our crystals are demonstrated by the absence of\u0000backscattering along with the linear energy dispersion of the dominant\u0000scattering vector. In addition, we detect non-dispersive scattering modes which\u0000we associate with bulk-surface scattering and, thus, allow an approximate\u0000identification of the bulk energy gap range based on our quasiparticle\u0000interference data. Measurements of differential conductance maps in magnetic\u0000fields up to 15 T have been carried out, but no strong modifications could be\u0000observed.","PeriodicalId":501211,"journal":{"name":"arXiv - PHYS - Other Condensed Matter","volume":"22 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142181826","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 study exciton energy spectrum and their propagation in moir'e superlattices formed in transition metal dichalcogenide heterobilayers. In such structures, as a result of weak interlayer interaction, an effective, moir'e, potential acting on excitons arises. Usually, excitons are considered to be localized in such potential. Here we demonstrate that the coupling of optically active excitons with induced electromagnetic field produces linear in the wavevector energy dispersion even if the quantum mechanical tunneling between the localization sites is suppressed. The effect can be described as a result of the processes of virtual generation-recombination of excitons at the localization sites that results in the $ r^{-3}$ dependence of the transfer matrix element on the intersite distance $r$. Based on the calculated energy spectrum we study exciton propagation in moir'e superlattices with allowance for the light-exciton interaction. We consider semiclassical diffusion of excitons and take into account exciton-phonon and exciton-static defect scattering. For these mechanisms the diffusion coefficient decreases with increase of the temperature. We also analyze the hopping propagation regime and demonstrate that the temperature dependence of the exciton diffusion coefficient is described by the power-law rather than by an exponential function of the temperature.
{"title":"Electromagnetic field assisted exciton diffusion in moiré superlattices","authors":"A. M. Shentsev, M. M. Glazov","doi":"arxiv-2409.04284","DOIUrl":"https://doi.org/arxiv-2409.04284","url":null,"abstract":"We study exciton energy spectrum and their propagation in moir'e\u0000superlattices formed in transition metal dichalcogenide heterobilayers. In such\u0000structures, as a result of weak interlayer interaction, an effective, moir'e,\u0000potential acting on excitons arises. Usually, excitons are considered to be\u0000localized in such potential. Here we demonstrate that the coupling of optically\u0000active excitons with induced electromagnetic field produces linear in the\u0000wavevector energy dispersion even if the quantum mechanical tunneling between\u0000the localization sites is suppressed. The effect can be described as a result\u0000of the processes of virtual generation-recombination of excitons at the\u0000localization sites that results in the $ r^{-3}$ dependence of the transfer\u0000matrix element on the intersite distance $r$. Based on the calculated energy\u0000spectrum we study exciton propagation in moir'e superlattices with allowance\u0000for the light-exciton interaction. We consider semiclassical diffusion of\u0000excitons and take into account exciton-phonon and exciton-static defect\u0000scattering. For these mechanisms the diffusion coefficient decreases with\u0000increase of the temperature. We also analyze the hopping propagation regime and\u0000demonstrate that the temperature dependence of the exciton diffusion\u0000coefficient is described by the power-law rather than by an exponential\u0000function of the temperature.","PeriodicalId":501211,"journal":{"name":"arXiv - PHYS - Other Condensed Matter","volume":"12 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142181831","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}
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