Pub Date : 2020-12-14DOI: 10.1103/PHYSREVRESEARCH.3.013201
A. Huam'an, Luis E. F. Foa Torres, C. Balseiro, G. Usaj
We report on the fate of the quantum Hall effect in graphene under strong laser illumination. By using Floquet theory combined with both a low energy description and full tight-binding models, we clarify the selection rules, the quasienergy band structure, as well as their connection with the two-terminal and multi-terminal conductance in a device setup as relevant for experiments. We show that the well-known dynamical gaps that appear in the Floquet spectrum at $pm,hbarOmega/2$ lead to a switch-off of the quantum Hall edge transport for different edge terminations except for the armchair one, where two terms cancel out exactly. More interestingly, we show that near the Dirac point changing the laser polarization (circular right or circular left) controls the Hall conductance, by allowing to switch it on or off, or even by flipping its sign, thereby reversing the chirality of the edge states. This might lead to new avenues to fully control topologically protected transport.
{"title":"Quantum Hall edge states under periodic driving: A Floquet induced chirality switch","authors":"A. Huam'an, Luis E. F. Foa Torres, C. Balseiro, G. Usaj","doi":"10.1103/PHYSREVRESEARCH.3.013201","DOIUrl":"https://doi.org/10.1103/PHYSREVRESEARCH.3.013201","url":null,"abstract":"We report on the fate of the quantum Hall effect in graphene under strong laser illumination. By using Floquet theory combined with both a low energy description and full tight-binding models, we clarify the selection rules, the quasienergy band structure, as well as their connection with the two-terminal and multi-terminal conductance in a device setup as relevant for experiments. We show that the well-known dynamical gaps that appear in the Floquet spectrum at $pm,hbarOmega/2$ lead to a switch-off of the quantum Hall edge transport for different edge terminations except for the armchair one, where two terms cancel out exactly. More interestingly, we show that near the Dirac point changing the laser polarization (circular right or circular left) controls the Hall conductance, by allowing to switch it on or off, or even by flipping its sign, thereby reversing the chirality of the edge states. This might lead to new avenues to fully control topologically protected transport.","PeriodicalId":8465,"journal":{"name":"arXiv: Mesoscale and Nanoscale Physics","volume":"55 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-12-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90817405","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 : 2020-12-14DOI: 10.1103/PhysRevB.103.235301
A. Vezvaee, G. Sharma, S. Economou, Edwin Barnes
The interplay of optical driving and hyperfine interaction between an electron confined in a quantum dot and its surrounding nuclear spin environment produces a range of interesting physics such as mode-locking. In this work, we go beyond the ubiquitous spin 1/2 approximation for nuclear spins and present a comprehensive theoretical framework for an optically driven electron spin in a self-assembled quantum dot coupled to a nuclear spin bath of arbitrary spin. Using a dynamical mean-field approach, we compute the nuclear spin polarization distribution with and without the quadrupolar coupling. We find that while hyperfine interactions drive dynamic nuclear polarization and mode-locking, quadrupolar couplings counteract these effects. The tension between these mechanisms is imprinted on the steady-state electron spin evolution, providing a way to measure the importance of quadrupolar interactions in a quantum dot. Our results show that higher-spin effects such as quadrupolar interactions can have a significant impact on the generation of dynamic nuclear polarization and how it influences the electron spin evolution.
{"title":"Driven dynamics of a quantum dot electron spin coupled to a bath of higher-spin nuclei","authors":"A. Vezvaee, G. Sharma, S. Economou, Edwin Barnes","doi":"10.1103/PhysRevB.103.235301","DOIUrl":"https://doi.org/10.1103/PhysRevB.103.235301","url":null,"abstract":"The interplay of optical driving and hyperfine interaction between an electron confined in a quantum dot and its surrounding nuclear spin environment produces a range of interesting physics such as mode-locking. In this work, we go beyond the ubiquitous spin 1/2 approximation for nuclear spins and present a comprehensive theoretical framework for an optically driven electron spin in a self-assembled quantum dot coupled to a nuclear spin bath of arbitrary spin. Using a dynamical mean-field approach, we compute the nuclear spin polarization distribution with and without the quadrupolar coupling. We find that while hyperfine interactions drive dynamic nuclear polarization and mode-locking, quadrupolar couplings counteract these effects. The tension between these mechanisms is imprinted on the steady-state electron spin evolution, providing a way to measure the importance of quadrupolar interactions in a quantum dot. Our results show that higher-spin effects such as quadrupolar interactions can have a significant impact on the generation of dynamic nuclear polarization and how it influences the electron spin evolution.","PeriodicalId":8465,"journal":{"name":"arXiv: Mesoscale and Nanoscale Physics","volume":"4 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-12-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74412799","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}
L. Banszerus, S. Moller, E. Icking, Corinne Steiner, Daniel Neumaier, Martin Otto, Kenji Watanabe, Takashi Taniguchi, Christian Volk, Christoph Stampfer
We demonstrate dispersive readout of individual charge states in a gate-defined few-electron quantum dot in bilayer graphene. We employ a radio frequency reflectometry circuit, where an LC resonator with a resonance frequency close to 280 MHz is directly coupled to an ohmic contact of the quantum dot device. The detection scheme based on changes in the quantum capacitance operates over a wide gate-voltage range and allows to probe excited states down to the single-electron regime. Crucially, the presented sensing technique avoids the use of an additional, capacitively coupled quantum device such as a quantum point contact or single electron transistor, making dispersive sensing particularly interesting for gate-defined graphene quantum dots.
{"title":"Dispersive sensing of charge states in a bilayer graphene quantum dot","authors":"L. Banszerus, S. Moller, E. Icking, Corinne Steiner, Daniel Neumaier, Martin Otto, Kenji Watanabe, Takashi Taniguchi, Christian Volk, Christoph Stampfer","doi":"10.1063/5.0040234","DOIUrl":"https://doi.org/10.1063/5.0040234","url":null,"abstract":"We demonstrate dispersive readout of individual charge states in a gate-defined few-electron quantum dot in bilayer graphene. We employ a radio frequency reflectometry circuit, where an LC resonator with a resonance frequency close to 280 MHz is directly coupled to an ohmic contact of the quantum dot device. The detection scheme based on changes in the quantum capacitance operates over a wide gate-voltage range and allows to probe excited states down to the single-electron regime. Crucially, the presented sensing technique avoids the use of an additional, capacitively coupled quantum device such as a quantum point contact or single electron transistor, making dispersive sensing particularly interesting for gate-defined graphene quantum dots.","PeriodicalId":8465,"journal":{"name":"arXiv: Mesoscale and Nanoscale Physics","volume":"38 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-12-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77316745","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 : 2020-12-10DOI: 10.1103/PHYSREVB.103.115142
Kevin A. Madsen, P. Brouwer, P. Recher, P. Silvestrov
The interaction of a magnetic insulator with the helical electronic edge of a two-dimensional topological insulator has been shown to lead to many interesting phenomena. One of these is that for a suitable orientation of the magnetic anisotropy axis, the exchange coupling to an easy-plane magnet has no effect on DC electrical transport through a helical edge, despite the fact that it opens a gap in the spectrum of the helical edge [Meng {em et al.}, Phys. Rev. B {bf 90}, 205403 (2014)]. Here, we theoretically consider such a magnet embedded in an interferometer, consisting of a pair of helical edge states connected by two tunneling contacts, at which electrons can tunnel between the two edges. Using a scattering matrix approach, we show that the presence of the magnet in one of the interferometer arms gives rise to AC currents in response to an applied DC voltage. On the other hand, the DC Aharonov-Bohm effect is absent at zero temperature and small DC voltages, and only appears if the applied voltage or the temperature exceeds the magnet-induced excitation gap.
磁性绝缘体与二维拓扑绝缘体的螺旋电子边的相互作用已被证明会导致许多有趣的现象。其中之一是，对于磁各向异性轴的合适方向，与易平面磁铁的交换耦合对通过螺旋边的直流电传输没有影响，尽管它在螺旋边的光谱中打开了一个间隙[Meng {em et al.}， Phys]。 Rev. B {bf 90}， 205403(2014)]。在这里，我们从理论上考虑这样一个嵌入在干涉仪中的磁铁，它由一对由两个隧道触点连接的螺旋边缘状态组成，电子可以在两个边缘之间隧穿。使用散射矩阵方法，我们表明，在干涉仪臂中的磁铁的存在会对施加的直流电压产生交流电流。另一方面，在零温度和小直流电压下，直流Aharonov-Bohm效应不存在，只有当外加电压或温度超过磁感应激励间隙时才会出现。
{"title":"Interference effects induced by a precessing easy-plane magnet coupled to a helical edge state","authors":"Kevin A. Madsen, P. Brouwer, P. Recher, P. Silvestrov","doi":"10.1103/PHYSREVB.103.115142","DOIUrl":"https://doi.org/10.1103/PHYSREVB.103.115142","url":null,"abstract":"The interaction of a magnetic insulator with the helical electronic edge of a two-dimensional topological insulator has been shown to lead to many interesting phenomena. One of these is that for a suitable orientation of the magnetic anisotropy axis, the exchange coupling to an easy-plane magnet has no effect on DC electrical transport through a helical edge, despite the fact that it opens a gap in the spectrum of the helical edge [Meng {em et al.}, Phys. Rev. B {bf 90}, 205403 (2014)]. Here, we theoretically consider such a magnet embedded in an interferometer, consisting of a pair of helical edge states connected by two tunneling contacts, at which electrons can tunnel between the two edges. Using a scattering matrix approach, we show that the presence of the magnet in one of the interferometer arms gives rise to AC currents in response to an applied DC voltage. On the other hand, the DC Aharonov-Bohm effect is absent at zero temperature and small DC voltages, and only appears if the applied voltage or the temperature exceeds the magnet-induced excitation gap.","PeriodicalId":8465,"journal":{"name":"arXiv: Mesoscale and Nanoscale Physics","volume":"36 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-12-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73993422","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}
C. X. Yu, S. Zihlmann, Gonzalo Troncoso Fernández-Bada, J. Thomassin, F. Gustavo, É. Dumur, R. Maurand
We characterize niobium nitride $lambda/2$ coplanar waveguide resonators, which were fabricated from a 10nm thick film on silicon dioxide grown by sputter deposition. For films grown at 120°C we report a superconducting critical temperature of 7.4K associated with a normal square resistance of 1k$Omega$ leading to a kinetic inductance of 192pH/$Box$. We fabricated resonators with a characteristic impedance up to 4.1k$Omega$ and internal quality factors $Q_mathrm{i} > 10^4$ in the single photon regime at zero magnetic field. Moreover, in the many photons regime, the resonators present high magnetic field resilience with $Q_mathrm{i} > 10^4$ in a 6T in-plane magnetic field as well as in a 300mT out-of-plane magnetic field. These findings make such resonators a compelling choice for cQED experiments involving quantum systems with small electric dipole moments operated in finite magnetic fields.
{"title":"Magnetic field resilient high kinetic inductance superconducting niobium nitride coplanar waveguide resonators","authors":"C. X. Yu, S. Zihlmann, Gonzalo Troncoso Fernández-Bada, J. Thomassin, F. Gustavo, É. Dumur, R. Maurand","doi":"10.1063/5.0039945","DOIUrl":"https://doi.org/10.1063/5.0039945","url":null,"abstract":"We characterize niobium nitride $lambda/2$ coplanar waveguide resonators, which were fabricated from a 10nm thick film on silicon dioxide grown by sputter deposition. For films grown at 120°C we report a superconducting critical temperature of 7.4K associated with a normal square resistance of 1k$Omega$ leading to a kinetic inductance of 192pH/$Box$. We fabricated resonators with a characteristic impedance up to 4.1k$Omega$ and internal quality factors $Q_mathrm{i} > 10^4$ in the single photon regime at zero magnetic field. Moreover, in the many photons regime, the resonators present high magnetic field resilience with $Q_mathrm{i} > 10^4$ in a 6T in-plane magnetic field as well as in a 300mT out-of-plane magnetic field. These findings make such resonators a compelling choice for cQED experiments involving quantum systems with small electric dipole moments operated in finite magnetic fields.","PeriodicalId":8465,"journal":{"name":"arXiv: Mesoscale and Nanoscale Physics","volume":"112 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-12-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76078989","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 : 2020-12-07DOI: 10.1103/PhysRevResearch.3.023033
L. Ginzburg, Carolin Gold, M. Röösli, C. Reichl, M. Berl, W. Wegscheider, T. Ihn, K. Ensslin
We measure electronic transport through point contacts in the high-mobility electron gas in a Ga[Al]As heterostructure at different temperatures and bulk electron densities. The conductance through all point contacts increases with increasing temperature in a temperature window around $T sim 10 K$ for all investigated electron densities and point contact widths. For high electron densities this conductance exceeds the fundamental ballistic limit (Sharvin limit). These observations are in agreement with a viscous electron transport model and previous experiments in graphene.
{"title":"Superballistic electron flow through a point contact in a Ga[Al]As heterostructure","authors":"L. Ginzburg, Carolin Gold, M. Röösli, C. Reichl, M. Berl, W. Wegscheider, T. Ihn, K. Ensslin","doi":"10.1103/PhysRevResearch.3.023033","DOIUrl":"https://doi.org/10.1103/PhysRevResearch.3.023033","url":null,"abstract":"We measure electronic transport through point contacts in the high-mobility electron gas in a Ga[Al]As heterostructure at different temperatures and bulk electron densities. The conductance through all point contacts increases with increasing temperature in a temperature window around $T sim 10 K$ for all investigated electron densities and point contact widths. For high electron densities this conductance exceeds the fundamental ballistic limit (Sharvin limit). These observations are in agreement with a viscous electron transport model and previous experiments in graphene.","PeriodicalId":8465,"journal":{"name":"arXiv: Mesoscale and Nanoscale Physics","volume":"258 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-12-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76206656","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 : 2020-12-07DOI: 10.1103/PhysRevB.103.L161411
Andrew Y. Joe, L. Jauregui, Kateryna Pistunova, Andrés M. Mier Valdivia, Zhengguang Lu, D. Wild, Giovanni Scuri, K. De Greve, Ryan J. Gelly, You Zhou, J. Sung, A. Sushko, T. Taniguchi, Kenji Watanabe, D. Smirnov, M. Lukin, Hongkun Park, P. Kim
Excitons are composite bosons that can feature spin singlet and triplet states. In usual semiconductors, without an additional spin-flip mechanism, triplet excitons are extremely inefficient optical emitters. Transition metal dichalcogenides (TMDs), with their large spin-orbit coupling, have been of special interest for valleytronic applications for their coupling of circularly polarized light to excitons with selective valley and spin$^{1-4}$. In atomically thin MoSe$_2$/WSe$_2$ TMD van der Waals (vdW) heterostructures, the unique atomic registry of vdW layers provides a quasi-angular momentum to interlayer excitons$^{5,6}$, enabling emission from otherwise dark spin triplet excitons. Here, we report electrically tunable spin singlet and triplet exciton emission from atomically aligned TMD heterostructures. We confirm the spin configurations of the light-emitting excitons employing magnetic fields to measure effective exciton g-factors. The interlayer tunneling current across the TMD vdW heterostructure enables the electrical generation of singlet and triplet exciton emission in this atomically thin PN junction. We demonstrate electrically tunability between the singlet and triplet excitons that are generated by charge injection. Atomically thin TMD heterostructure light emitting diodes thus enables a route for optoelectronic devices that can configure spin and valley quantum states independently by controlling the atomic stacking registry.
激子是复合玻色子，具有自旋单重态和三重态。在通常的半导体中，没有额外的自旋翻转机制，三重态激子是极低效的光发射器。过渡金属二硫族化合物(TMDs)具有较大的自旋-轨道耦合，可使圆偏振光与具有选择性谷和自旋$^{1-4}$的激子耦合，在谷电子应用中具有特殊的意义。在原子薄的MoSe$_2$/WSe$_2$ TMD van der Waals (vdW)异质结构中，vdW层独特的原子注册为层间激子$^{5,6}$提供了准角动量，从而使暗自旋三重态激子能够发射。在这里，我们报道了从原子排列的TMD异质结构中电可调谐的自旋单重态和三重态激子发射。我们利用磁场测量有效激子g因子，证实了发光激子的自旋构型。通过TMD vdW异质结构的层间隧道电流使得在这个原子薄的PN结中产生单线态和三重态激子发射。我们证明了由电荷注入产生的单重态和三重态激子之间的电可调性。因此，原子薄TMD异质结构发光二极管为光电子器件提供了一条途径，该器件可以通过控制原子堆叠注册来独立配置自旋和谷量子态。
{"title":"Electrically controlled emission from singlet and triplet exciton species in atomically thin light-emitting diodes","authors":"Andrew Y. Joe, L. Jauregui, Kateryna Pistunova, Andrés M. Mier Valdivia, Zhengguang Lu, D. Wild, Giovanni Scuri, K. De Greve, Ryan J. Gelly, You Zhou, J. Sung, A. Sushko, T. Taniguchi, Kenji Watanabe, D. Smirnov, M. Lukin, Hongkun Park, P. Kim","doi":"10.1103/PhysRevB.103.L161411","DOIUrl":"https://doi.org/10.1103/PhysRevB.103.L161411","url":null,"abstract":"Excitons are composite bosons that can feature spin singlet and triplet states. In usual semiconductors, without an additional spin-flip mechanism, triplet excitons are extremely inefficient optical emitters. Transition metal dichalcogenides (TMDs), with their large spin-orbit coupling, have been of special interest for valleytronic applications for their coupling of circularly polarized light to excitons with selective valley and spin$^{1-4}$. In atomically thin MoSe$_2$/WSe$_2$ TMD van der Waals (vdW) heterostructures, the unique atomic registry of vdW layers provides a quasi-angular momentum to interlayer excitons$^{5,6}$, enabling emission from otherwise dark spin triplet excitons. Here, we report electrically tunable spin singlet and triplet exciton emission from atomically aligned TMD heterostructures. We confirm the spin configurations of the light-emitting excitons employing magnetic fields to measure effective exciton g-factors. The interlayer tunneling current across the TMD vdW heterostructure enables the electrical generation of singlet and triplet exciton emission in this atomically thin PN junction. We demonstrate electrically tunability between the singlet and triplet excitons that are generated by charge injection. Atomically thin TMD heterostructure light emitting diodes thus enables a route for optoelectronic devices that can configure spin and valley quantum states independently by controlling the atomic stacking registry.","PeriodicalId":8465,"journal":{"name":"arXiv: Mesoscale and Nanoscale Physics","volume":"5 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-12-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84568512","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 : 2020-12-07DOI: 10.1103/PhysRevB.103.195440
D. Smirnov, A. Shumilin
We demonstrate that nuclear spin fluctuations lead to the electric current noise in the mesoscopic samples of organic semiconductors showing the pronounced magnetoresistance in weak fields. For the bipolaron and electron-hole mechanisms of organic magnetoresistance, the current noise spectrum consists of the high frequency peak related to the nuclear spin precession in the Knight field of the charge carriers and the low frequency peak related to the nuclear spin relaxation. The shape of the spectrum depends on the external magnetic and radiofrequency fields, which allows one to prove the role of nuclei in magnetoresistance experimentally.
{"title":"Electric current noise in mesoscopic organic semiconductors induced by nuclear spin fluctuations","authors":"D. Smirnov, A. Shumilin","doi":"10.1103/PhysRevB.103.195440","DOIUrl":"https://doi.org/10.1103/PhysRevB.103.195440","url":null,"abstract":"We demonstrate that nuclear spin fluctuations lead to the electric current noise in the mesoscopic samples of organic semiconductors showing the pronounced magnetoresistance in weak fields. For the bipolaron and electron-hole mechanisms of organic magnetoresistance, the current noise spectrum consists of the high frequency peak related to the nuclear spin precession in the Knight field of the charge carriers and the low frequency peak related to the nuclear spin relaxation. The shape of the spectrum depends on the external magnetic and radiofrequency fields, which allows one to prove the role of nuclei in magnetoresistance experimentally.","PeriodicalId":8465,"journal":{"name":"arXiv: Mesoscale and Nanoscale Physics","volume":"111 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-12-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"91362440","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 : 2020-12-05DOI: 10.1103/PhysRevB.103.235416
J. Barański, M. Barańska, T. Zienkiewicz, R. Taranko, T. Domański
We study a hybrid structure, comprising the single-level quantum dot attached to the topological superconducting nanowire, inspecting dynamical transfer of the Majorana quasiparticle onto normal region. Motivated by the recent experimental realization of such heterostructure and its investigation under the stationary conditions [L. Schneider et al., https://doi.org/10.1038/s41467-020-18540-3, Nature Communications 11, 4707 (2020)] where the quantum dot energy level can be tuned by gate potential we examine how much time is needed for the Majorana mode to leak into the normal region. We estimate, that for typical hybrid structures this dynamical process would take about 20 nanoseconds. We propose a feasible empirical protocol for its detection by means of the time-resolved Andreev tunneling spectroscopy.
{"title":"Dynamical leakage of Majorana mode into side-attached quantum dot","authors":"J. Barański, M. Barańska, T. Zienkiewicz, R. Taranko, T. Domański","doi":"10.1103/PhysRevB.103.235416","DOIUrl":"https://doi.org/10.1103/PhysRevB.103.235416","url":null,"abstract":"We study a hybrid structure, comprising the single-level quantum dot attached to the topological superconducting nanowire, inspecting dynamical transfer of the Majorana quasiparticle onto normal region. Motivated by the recent experimental realization of such heterostructure and its investigation under the stationary conditions [L. Schneider et al., https://doi.org/10.1038/s41467-020-18540-3, Nature Communications 11, 4707 (2020)] where the quantum dot energy level can be tuned by gate potential we examine how much time is needed for the Majorana mode to leak into the normal region. We estimate, that for typical hybrid structures this dynamical process would take about 20 nanoseconds. We propose a feasible empirical protocol for its detection by means of the time-resolved Andreev tunneling spectroscopy.","PeriodicalId":8465,"journal":{"name":"arXiv: Mesoscale and Nanoscale Physics","volume":"20 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-12-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82951868","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 : 2020-12-05DOI: 10.1103/PhysRevB.103.174410
R. Jaeschke-Ubiergo, E. S. Morell, A. S. Nunez
We study the microscopical origin of anisotropic ferromagnetism in the van der Waals magnet CrI3. We conclude that the nearest neighbors exchange is well described by the Heisenberg-Kitaev-Gamma (HKGamma) model, and we also found a nonzero Dzyaloshinskii-Moriya interaction (DMI) on next nearest neighbors. Both Kitaev and DMI are known to generate a non-trivial topology of the magnons in the honeycomb lattice and have been used separately to describe the low energy regime of this material. We discuss that including one or the other leads to different signs of the Chern number. Furthermore, the topological gap at K-point seems to be mainly produced by DMI, despite it is one order of magnitude smaller than Kitaev. Finally, we show that by applying an external electric field perpendicular to the crystal plane, it is possible to induce DMI on nearest neighbors, and this could have consequences in non-collinear spin textures, such as domain walls and skyrmions.
{"title":"Theory of magnetism in the van der Waals magnet CrI3.","authors":"R. Jaeschke-Ubiergo, E. S. Morell, A. S. Nunez","doi":"10.1103/PhysRevB.103.174410","DOIUrl":"https://doi.org/10.1103/PhysRevB.103.174410","url":null,"abstract":"We study the microscopical origin of anisotropic ferromagnetism in the van der Waals magnet CrI3. We conclude that the nearest neighbors exchange is well described by the Heisenberg-Kitaev-Gamma (HKGamma) model, and we also found a nonzero Dzyaloshinskii-Moriya interaction (DMI) on next nearest neighbors. Both Kitaev and DMI are known to generate a non-trivial topology of the magnons in the honeycomb lattice and have been used separately to describe the low energy regime of this material. We discuss that including one or the other leads to different signs of the Chern number. Furthermore, the topological gap at K-point seems to be mainly produced by DMI, despite it is one order of magnitude smaller than Kitaev. Finally, we show that by applying an external electric field perpendicular to the crystal plane, it is possible to induce DMI on nearest neighbors, and this could have consequences in non-collinear spin textures, such as domain walls and skyrmions.","PeriodicalId":8465,"journal":{"name":"arXiv: Mesoscale and Nanoscale Physics","volume":"15 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-12-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87813440","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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