Pub Date : 2021-09-27DOI: 10.1038/s41598-021-96592-1DOI: 10.1038/s41598-021-96592-1 10.1038/s41598-021-96592-1
Kallol Mondal, S. Ganguly, S. Maiti
{"title":"A driven fractal network: Possible route to efficient thermoelectric application","authors":"Kallol Mondal, S. Ganguly, S. Maiti","doi":"10.1038/s41598-021-96592-1DOI: 10.1038/s41598-021-96592-1 10.1038/s41598-021-96592-1","DOIUrl":"https://doi.org/10.1038/s41598-021-96592-1DOI: 10.1038/s41598-021-96592-1 10.1038/s41598-021-96592-1","url":null,"abstract":"","PeriodicalId":8465,"journal":{"name":"arXiv: Mesoscale and Nanoscale Physics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-09-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84754638","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}
Pub Date : 2021-08-23DOI: 10.21203/rs.3.rs-871457/v1
S. Phark, Yi Chen, C. Wolf, H. Bui, Yu Wang, M. Haze, Jinkyung Kim, C. Lutz, A. Heinrich, Yujeong Bae
Atomic-scale control of multiple spins with individual addressability enables the bottom-up design of functional quantum devices. Tailored nanostructures can be built with atomic precision using scanning tunneling microscopes, but quantum-coherent driving has thus far been limited to a spin in the tunnel junction. Here we show the ability to drive and detect the spin resonance of a remote spin using the electric field from the tip and a single-atom magnet placed nearby. Read-out was achieved via a weakly coupled second spin in the tunnel junction that acted as a quantum sensor. We simultaneously and independently drove the sensor and remote spins by two radio frequency voltages in double resonance experiments, which provides a path to quantum-coherent multi-spin manipulation in customized spin structures on surfaces. One-Sentence Summary: Using a scanning tunneling microscope, we simultaneously control two spins using one tip, paving the way for multi-spin-qubit operations on surfaces.
{"title":"Double Electron Spin Resonance of Engineered Atomic Structures on a Surface","authors":"S. Phark, Yi Chen, C. Wolf, H. Bui, Yu Wang, M. Haze, Jinkyung Kim, C. Lutz, A. Heinrich, Yujeong Bae","doi":"10.21203/rs.3.rs-871457/v1","DOIUrl":"https://doi.org/10.21203/rs.3.rs-871457/v1","url":null,"abstract":"\u0000 Atomic-scale control of multiple spins with individual addressability enables the bottom-up design of functional quantum devices. Tailored nanostructures can be built with atomic precision using scanning tunneling microscopes, but quantum-coherent driving has thus far been limited to a spin in the tunnel junction. Here we show the ability to drive and detect the spin resonance of a remote spin using the electric field from the tip and a single-atom magnet placed nearby. Read-out was achieved via a weakly coupled second spin in the tunnel junction that acted as a quantum sensor. We simultaneously and independently drove the sensor and remote spins by two radio frequency voltages in double resonance experiments, which provides a path to quantum-coherent multi-spin manipulation in customized spin structures on surfaces. One-Sentence Summary: Using a scanning tunneling microscope, we simultaneously control two spins using one tip, paving the way for multi-spin-qubit operations on surfaces.","PeriodicalId":8465,"journal":{"name":"arXiv: Mesoscale and Nanoscale Physics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-08-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80189984","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}
Pub Date : 2021-07-22DOI: 10.21203/RS.3.RS-736619/V1
J. Gartside, K. Stenning, A. Vanstone, T. Dion, Holly H. Holder, D. Arroo, H. Kurebayashi, W. Branford
Strongly-interacting artificial spin systems are moving beyond mimicking naturally-occurring materials to find roles as versatile functional platforms, from reconfigurable magnonics to designer magnetic metamaterials. Typically artificial spin systems comprise nanomagnets with a single magnetisation texture: collinear macrospins or chiral vortices. By tuning nanoarray dimensions we achieve macrospin/vortex bistability and demonstrate a four-state metamaterial spin-system ‘Artificial Spin-Vortex Ice’ (ASVI). ASVI is capable of adopting Ising-like macrospins with strong ice-like vertex interactions, in addition to weakly-coupled vortices with low stray dipolar-field. The enhanced bi-texture microstate space gives rise to emergent physical memory phenomena, with ratchet-like vortex training and history-dependent nonlinear training dynamics. We observe vortex-domain formation alongside MFM tip vortex-writing. Tip-written vortices dramatically alter local reversal and memory dynamics. Vortices and macrospins exhibit starkly-differing spin-wave spectra with analogue-style mode-amplitude control via vortex training and mode-frequency shifts of ∆f = 3.8 GHz. We leverage spin-wave ‘spectral fingerprinting’ for rapid, scaleable readout of vortex and macrospin populations over complex training-protocols with applicability for functional magnonics and physical memory.
{"title":"Reconfigurable Training, Vortex Writing and Spin-Wave Fingerprinting in an Artificial Spin-Vortex Ice","authors":"J. Gartside, K. Stenning, A. Vanstone, T. Dion, Holly H. Holder, D. Arroo, H. Kurebayashi, W. Branford","doi":"10.21203/RS.3.RS-736619/V1","DOIUrl":"https://doi.org/10.21203/RS.3.RS-736619/V1","url":null,"abstract":"\u0000 Strongly-interacting artificial spin systems are moving beyond mimicking naturally-occurring materials to find roles as versatile functional platforms, from reconfigurable magnonics to designer magnetic metamaterials. Typically artificial spin systems comprise nanomagnets with a single magnetisation texture: collinear macrospins or chiral vortices. By tuning nanoarray dimensions we achieve macrospin/vortex bistability and demonstrate a four-state metamaterial spin-system ‘Artificial Spin-Vortex Ice’ (ASVI). ASVI is capable of adopting Ising-like macrospins with strong ice-like vertex interactions, in addition to weakly-coupled vortices with low stray dipolar-field. The enhanced bi-texture microstate space gives rise to emergent physical memory phenomena, with ratchet-like vortex training and history-dependent nonlinear training dynamics. We observe vortex-domain formation alongside MFM tip vortex-writing. Tip-written vortices dramatically alter local reversal and memory dynamics. Vortices and macrospins exhibit starkly-differing spin-wave spectra with analogue-style mode-amplitude control via vortex training and mode-frequency shifts of ∆f = 3.8 GHz. We leverage spin-wave ‘spectral fingerprinting’ for rapid, scaleable readout of vortex and macrospin populations over complex training-protocols with applicability for functional magnonics and physical memory.","PeriodicalId":8465,"journal":{"name":"arXiv: Mesoscale and Nanoscale Physics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-07-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86828126","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}
Pub Date : 2021-06-01DOI: 10.21203/RS.3.RS-490959/V1
Yan Duan, J. Coutinho, Lorena E. Rosaleny, S. Cardona, José J. Baldoví, A. Gaita-Ariño
Two decades of intensive research in lanthanide-based molecular nanomagnets have brought the magnetic memory in molecules from liquid helium to liquid nitrogen temperature. In the pursuit of new derivatives with improved operational temperatures, several "rational" strategies have been proposed and applied through a fluid transfer of knowledge between theoreticians and experimentalists. These have mainly focused on the choice of the magnetic ion and the design of an adequate coordination environment, both in terms of magnetic anisotropy and molecular vibrations. However, much of the progress has been achieved by serendipity, oversimplified theories and chemical intuition. In order to draw conclusions on the chemical design key parameters that govern the physical behavior of molecular nanomagnets in terms of magnetic memory, we apply here a state-of-the-art inferential statistical analysis to a body of over a thousand published experiments. Our analysis shows that the effective barrier derived from an Arrhenius equation displays an excellent correlation with the magnetic memory, and that there are only two promising strategies between all alternatives proposed so far, namely terbium bis-phthalocyaninato sandwiches and dysprosium metallocenes. In addition, we provide an interactive dashboard for visualizing the collected data, which contains all the reported cases between 2003 and 2019. This meta-study aims to dispel widespread theoretical misconceptions and will allow researchers in the field to avoid experimental blind alleys.
{"title":"Data mining, dashboards and statistics: a powerful framework for the chemical design of molecular nanomagnets","authors":"Yan Duan, J. Coutinho, Lorena E. Rosaleny, S. Cardona, José J. Baldoví, A. Gaita-Ariño","doi":"10.21203/RS.3.RS-490959/V1","DOIUrl":"https://doi.org/10.21203/RS.3.RS-490959/V1","url":null,"abstract":"Two decades of intensive research in lanthanide-based molecular nanomagnets have brought the magnetic memory in molecules from liquid helium to liquid nitrogen temperature. In the pursuit of new derivatives with improved operational temperatures, several \"rational\" strategies have been proposed and applied through a fluid transfer of knowledge between theoreticians and experimentalists. These have mainly focused on the choice of the magnetic ion and the design of an adequate coordination environment, both in terms of magnetic anisotropy and molecular vibrations. However, much of the progress has been achieved by serendipity, oversimplified theories and chemical intuition. In order to draw conclusions on the chemical design key parameters that govern the physical behavior of molecular nanomagnets in terms of magnetic memory, we apply here a state-of-the-art inferential statistical analysis to a body of over a thousand published experiments. Our analysis shows that the effective barrier derived from an Arrhenius equation displays an excellent correlation with the magnetic memory, and that there are only two promising strategies between all alternatives proposed so far, namely terbium bis-phthalocyaninato sandwiches and dysprosium metallocenes. In addition, we provide an interactive dashboard for visualizing the collected data, which contains all the reported cases between 2003 and 2019. This meta-study aims to dispel widespread theoretical misconceptions and will allow researchers in the field to avoid experimental blind alleys.","PeriodicalId":8465,"journal":{"name":"arXiv: Mesoscale and Nanoscale Physics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80357830","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}
Pub Date : 2021-05-09DOI: 10.3929/ETHZ-B-000482685
I. Schwartz, Y. Shimazaki
Moire superlattices in twisted transition metal dichalcogenide bilayers have emerged as a rich platform for exploring strong correlations using optical spectroscopy. Despite observation of rich Mott-Wigner physics stemming from an interplay between the periodic potential and Coulomb interactions, the absence of tunnel coupling induced hybridization of electronic states ensured a classical layer degree of freedom in these experiments. Here, we investigate a MoSe$_2$ homobilayer structure where inter-layer coherent tunnelling and layer-selective optical transitions allow for electric field controlled manipulation and measurement of the layer-pseudospin of the ground-state holes. A striking example of qualitatively new phenomena in this system is our observation of an electrically tunable 2D Feshbach resonance in exciton-hole scattering, which allows us to control the strength of interactions between excitons and holes located in different layers. Our findings enable hitherto unexplored possibilities for optical investigation of many-body physics, as well as realization of degenerate Bose-Fermi mixtures with tunable interactions, without directly exposing the itinerant fermions to light fields.
{"title":"Observation of electrically tunable Feshbach resonances in twisted bilayer semiconductors","authors":"I. Schwartz, Y. Shimazaki","doi":"10.3929/ETHZ-B-000482685","DOIUrl":"https://doi.org/10.3929/ETHZ-B-000482685","url":null,"abstract":"Moire superlattices in twisted transition metal dichalcogenide bilayers have emerged as a rich platform for exploring strong correlations using optical spectroscopy. Despite observation of rich Mott-Wigner physics stemming from an interplay between the periodic potential and Coulomb interactions, the absence of tunnel coupling induced hybridization of electronic states ensured a classical layer degree of freedom in these experiments. Here, we investigate a MoSe$_2$ homobilayer structure where inter-layer coherent tunnelling and layer-selective optical transitions allow for electric field controlled manipulation and measurement of the layer-pseudospin of the ground-state holes. A striking example of qualitatively new phenomena in this system is our observation of an electrically tunable 2D Feshbach resonance in exciton-hole scattering, which allows us to control the strength of interactions between excitons and holes located in different layers. Our findings enable hitherto unexplored possibilities for optical investigation of many-body physics, as well as realization of degenerate Bose-Fermi mixtures with tunable interactions, without directly exposing the itinerant fermions to light fields.","PeriodicalId":8465,"journal":{"name":"arXiv: Mesoscale and Nanoscale Physics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-05-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85150783","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}
Pub Date : 2021-04-18DOI: 10.1103/PhysRevB.104.075303
D. Ziemkiewicz, G. Czajkowski, Karol Karpi'nski, S. Z. -. Raczy'nska
We present theoretical results of the calculations of optical functions for Cu$_2$O quantum well (QW) with Rydberg excitons in an external homogeneous electric field of an arbitrary field strength. Two configurations of an external electric field perpendicular and parallel to the QW planes are considered in the energetic region for discrete excitonic states and continuum states. With the help of the real density matrix approach, which enables the derivation of the analytical expressions for the QW electro-optical functions, absorption spectra are calculated for the case of the excitation energy below the gap energy.
{"title":"Electro-optical properties of excitons in Cu$_2$O quantum wells: I discrete states.","authors":"D. Ziemkiewicz, G. Czajkowski, Karol Karpi'nski, S. Z. -. Raczy'nska","doi":"10.1103/PhysRevB.104.075303","DOIUrl":"https://doi.org/10.1103/PhysRevB.104.075303","url":null,"abstract":"We present theoretical results of the calculations of optical functions for Cu$_2$O quantum well (QW) with Rydberg excitons in an external homogeneous electric field of an arbitrary field strength. Two configurations of an external electric field perpendicular and parallel to the QW planes are considered in the energetic region for discrete excitonic states and continuum states. With the help of the real density matrix approach, which enables the derivation of the analytical expressions for the QW electro-optical functions, absorption spectra are calculated for the case of the excitation energy below the gap energy.","PeriodicalId":8465,"journal":{"name":"arXiv: Mesoscale and Nanoscale Physics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-04-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89271496","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}
Pub Date : 2021-04-12DOI: 10.1103/PhysRevB.106.035107
Yanbang Chu, Le Liu, Cheng Shen, Jinpeng Tian, Jian Tang, Yanchong Zhao, Jieying Liu, Yalong Yuan, Y. Ji, Rong Yang, Kenji Watanabe, T. Taniguchi, D. Shi, Fengcheng Wu, Wei Yang, Guangyu Zhang
Twisted double bilayer graphene (TDBG) is an electric-field-tunable moiré system, exhibiting electron correlated states and related temperature linear (T-linear) resistivity. The displacement field provides a new knob to in-situ tune the relative strength of electron interactions in TDBG, yielding not only a rich phase diagram but also the ability to investigate each phase individually. Here, we report a study of carrier density (n), displacement field (D) and twist angle (θ) dependence of T-linear resistivity in TDBG. For a large twist angle (θ > 1.5°) where correlated insulating states are absent, we observe a T-linear resistivity (order of 10Ω/K) over a wide range of carrier density and its slope decreases with increasing of n before reaching the van Hove singularity, in agreement with acoustic phonon scattering model. The slope of T-linear resistivity is non-monotonically dependent on displacement field, with a single peak structure closely connected to single-particle van Hove Singularity (vHS) in TDBG. For an optimal twist angle of ~ 1.23° in the presence of correlated states, the slope of T-linear resistivity is found maximum at the boundary of the correlated halo regime (order of 100Ω/K), resulting a ‘M’ shape displacement field dependence. The observation is beyond the phonon scattering model from single particle picture, and instead it suggests a strange metal behavior. We interpret the observation as a result of symmetry-breaking instability developed at quantum critical points where electron degeneracy changes. Our results demonstrate that TDBG is an ideal system to study the interplay between phonon and quantum criticality, and might help to map out the evolution of the order parameters for the ground states.
{"title":"Phonons and Quantum Criticality Revealed by Temperature Linear Resistivity in Twisted Double Bilayer Graphene","authors":"Yanbang Chu, Le Liu, Cheng Shen, Jinpeng Tian, Jian Tang, Yanchong Zhao, Jieying Liu, Yalong Yuan, Y. Ji, Rong Yang, Kenji Watanabe, T. Taniguchi, D. Shi, Fengcheng Wu, Wei Yang, Guangyu Zhang","doi":"10.1103/PhysRevB.106.035107","DOIUrl":"https://doi.org/10.1103/PhysRevB.106.035107","url":null,"abstract":"\u0000 Twisted double bilayer graphene (TDBG) is an electric-field-tunable moiré system, exhibiting electron correlated states and related temperature linear (T-linear) resistivity. The displacement field provides a new knob to in-situ tune the relative strength of electron interactions in TDBG, yielding not only a rich phase diagram but also the ability to investigate each phase individually. Here, we report a study of carrier density (n), displacement field (D) and twist angle (θ) dependence of T-linear resistivity in TDBG. For a large twist angle (θ > 1.5°) where correlated insulating states are absent, we observe a T-linear resistivity (order of 10Ω/K) over a wide range of carrier density and its slope decreases with increasing of n before reaching the van Hove singularity, in agreement with acoustic phonon scattering model. The slope of T-linear resistivity is non-monotonically dependent on displacement field, with a single peak structure closely connected to single-particle van Hove Singularity (vHS) in TDBG. For an optimal twist angle of ~ 1.23° in the presence of correlated states, the slope of T-linear resistivity is found maximum at the boundary of the correlated halo regime (order of 100Ω/K), resulting a ‘M’ shape displacement field dependence. The observation is beyond the phonon scattering model from single particle picture, and instead it suggests a strange metal behavior. We interpret the observation as a result of symmetry-breaking instability developed at quantum critical points where electron degeneracy changes. Our results demonstrate that TDBG is an ideal system to study the interplay between phonon and quantum criticality, and might help to map out the evolution of the order parameters for the ground states.","PeriodicalId":8465,"journal":{"name":"arXiv: Mesoscale and Nanoscale Physics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-04-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73428948","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}
Pub Date : 2021-03-24DOI: 10.21203/RS.3.RS-321169/V1
N. Ligato, E. Strambini, F. Paolucci, F. Giazotto
Superconducting computing promises enhanced computational power in both classical and quantum approaches. Yet, efficient schemes for scalable and fast superconducting memories are still missing. On the one hand, the large inductance required in magnetic flux-controlled Josephson memories impedes device miniaturization. On the other hand, the use of ferromagnetic order to store information often degrades superconductivity, and limits the operation speed to the magnetization switching rate of a few GHz. Here, we overcome the above limitations through a fully superconducting memory cell based on the topological transition driven by hysteretic phase slips existing in aluminum nanowire Josephson junctions. Our direct and non-destructive read-out scheme, based on local tunneling spectroscopy, ensures reduced dissipation ($lesssim 40$ fW) and estimated response time below $lesssim 30$ ps thereby yielding a maximum energy per bit consumption as low as $sim 10^{-24}$ J. In addition, the memory topological index can be directly read by robust phase measurements thus further lowering dissipation whilst maximizing the stability against magnetic noise. The memory, measured over several days, showed no evidence of information degradation up to $sim 1.1$ K, i.e., $sim 85%$ of the critical temperature of aluminum. The ease of operation combined with remarkable performance elects the Josephson phase-slip memory as an attractive storage cell to be exploited in advanced superconducting logic architectures.
{"title":"Persistent Josephson Phase-Slip Memory with Topological Protection","authors":"N. Ligato, E. Strambini, F. Paolucci, F. Giazotto","doi":"10.21203/RS.3.RS-321169/V1","DOIUrl":"https://doi.org/10.21203/RS.3.RS-321169/V1","url":null,"abstract":"Superconducting computing promises enhanced computational power in both classical and quantum approaches. Yet, efficient schemes for scalable and fast superconducting memories are still missing. On the one hand, the large inductance required in magnetic flux-controlled Josephson memories impedes device miniaturization. On the other hand, the use of ferromagnetic order to store information often degrades superconductivity, and limits the operation speed to the magnetization switching rate of a few GHz. Here, we overcome the above limitations through a fully superconducting memory cell based on the topological transition driven by hysteretic phase slips existing in aluminum nanowire Josephson junctions. Our direct and non-destructive read-out scheme, based on local tunneling spectroscopy, ensures reduced dissipation ($lesssim 40$ fW) and estimated response time below $lesssim 30$ ps thereby yielding a maximum energy per bit consumption as low as $sim 10^{-24}$ J. In addition, the memory topological index can be directly read by robust phase measurements thus further lowering dissipation whilst maximizing the stability against magnetic noise. The memory, measured over several days, showed no evidence of information degradation up to $sim 1.1$ K, i.e., $sim 85%$ of the critical temperature of aluminum. The ease of operation combined with remarkable performance elects the Josephson phase-slip memory as an attractive storage cell to be exploited in advanced superconducting logic architectures.","PeriodicalId":8465,"journal":{"name":"arXiv: Mesoscale and Nanoscale Physics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-03-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75788848","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}
Pub Date : 2021-03-12DOI: 10.21203/RS.3.RS-556743/V1
W. Kang, Felix Spathelf, B. Fauqu'e, Y. Fuseya, Kamran Behnia
The interface between a solid and vacuum can become electronically distinct from the bulk. This feature, encountered in the case of quantum Hall effect, has a manifestation in insulators with topologically protected metallic surface states. Non-trivial Berry curvature of the Bloch waves or periodically driven perturbation are known to generate it. Here, by studying the angle-dependent magnetoresistance in prismatic bismuth crystals of different shapes, we detect a robust surface contribution to electric conductivity when the magnetic field is aligned parallel to a two-dimensional boundary between the three-dimensional crystal and vacuum. The effect is absent in antimony, which has an identical crystal symmetry, a similar Fermi surface structure and equally ballistic carriers, but an inverted band symmetry and a topological invariant of opposite sign. Our observation points to the relevance of band symmetries to survival of metallicity at the boundary interrupting the cyclotron orbits.
{"title":"Boundary conductance protected by topology in macroscopic bismuth crystals","authors":"W. Kang, Felix Spathelf, B. Fauqu'e, Y. Fuseya, Kamran Behnia","doi":"10.21203/RS.3.RS-556743/V1","DOIUrl":"https://doi.org/10.21203/RS.3.RS-556743/V1","url":null,"abstract":"\u0000 The interface between a solid and vacuum can become electronically distinct from the bulk. This feature, encountered in the case of quantum Hall effect, has a manifestation in insulators with topologically protected metallic surface states. Non-trivial Berry curvature of the Bloch waves or periodically driven perturbation are known to generate it. Here, by studying the angle-dependent magnetoresistance in prismatic bismuth crystals of different shapes, we detect a robust surface contribution to electric conductivity when the magnetic field is aligned parallel to a two-dimensional boundary between the three-dimensional crystal and vacuum. The effect is absent in antimony, which has an identical crystal symmetry, a similar Fermi surface structure and equally ballistic carriers, but an inverted band symmetry and a topological invariant of opposite sign. Our observation points to the relevance of band symmetries to survival of metallicity at the boundary interrupting the cyclotron orbits.","PeriodicalId":8465,"journal":{"name":"arXiv: Mesoscale and Nanoscale Physics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-03-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75205155","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}
Pub Date : 2021-03-01DOI: 10.21203/RS.3.RS-228103/V1
Y. Choi, M. Doan, Youngkuk Kim, G. Choi
The ordinary Hall effect refers to generation of a transverse voltage upon exertion of an electric field in the presence of an out-of-plane magnetic field. While a linear Hall effect is commonly observed in systems with breaking time-reversal symmetry via an applied external magnetic field or their intrinsic magnetization1, 2, a nonlinear Hall effect can generically occur in non-magnetic systems associated with a nonvanishing Berry curvature dipole3. Here we report, observations of a nonlinear optical Hall effect in a Weyl semimetal WTe2 without an applied magnetic field at room temperature. We observe an optical Hall effect resulting in a polarization rotation of the reflected light, referred to as the nonlinear Kerr rotation. The nonlinear Kerr rotation linearly depends on the charge current and optical power, which manifests the fourth-order nonlinearity. We quantitatively determine the fourth-order susceptibility, which exhibits strong anisotropy depending on the directions of the charge current and the light polarization. Employing symmetry analysis of Berry curvature multipoles, we demonstrate that the nonlinear Kerr rotations can arise from the Berry curvature hexapole allowed by the crystalline symmetries of WTe2. There also exist marginal signals that are incompatible with the symmetries, which suggest a hidden phase associated with the nonlinear process.
{"title":"Nonlinear optical Hall effect in Weyl semimetal WTe2","authors":"Y. Choi, M. Doan, Youngkuk Kim, G. Choi","doi":"10.21203/RS.3.RS-228103/V1","DOIUrl":"https://doi.org/10.21203/RS.3.RS-228103/V1","url":null,"abstract":"\u0000 The ordinary Hall effect refers to generation of a transverse voltage upon exertion of an electric field in the presence of an out-of-plane magnetic field. While a linear Hall effect is commonly observed in systems with breaking time-reversal symmetry via an applied external magnetic field or their intrinsic magnetization1, 2, a nonlinear Hall effect can generically occur in non-magnetic systems associated with a nonvanishing Berry curvature dipole3. Here we report, observations of a nonlinear optical Hall effect in a Weyl semimetal WTe2 without an applied magnetic field at room temperature. We observe an optical Hall effect resulting in a polarization rotation of the reflected light, referred to as the nonlinear Kerr rotation. The nonlinear Kerr rotation linearly depends on the charge current and optical power, which manifests the fourth-order nonlinearity. We quantitatively determine the fourth-order susceptibility, which exhibits strong anisotropy depending on the directions of the charge current and the light polarization. Employing symmetry analysis of Berry curvature multipoles, we demonstrate that the nonlinear Kerr rotations can arise from the Berry curvature hexapole allowed by the crystalline symmetries of WTe2. There also exist marginal signals that are incompatible with the symmetries, which suggest a hidden phase associated with the nonlinear process.","PeriodicalId":8465,"journal":{"name":"arXiv: Mesoscale and Nanoscale Physics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79323854","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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