Quenching of the quantum Hall effect in graphene with scrolled edges

Quenching of Spin Hall Effect in Ballistic nano-junctions

We show that a nanometric four-probe ballistic junction can be used to check the presence of a transverse spin Hall current in a system with a Spin Orbit coupling not of the Rashba type, but rather due to the in-plane electric field. Indeed, the spin Hall effect is due to the presence of an effective small transverse magnetic field corresponding to the Spin Orbit coupling generated by the confining potential. The strength of the field and the junction shape characterize the quenching Hall regime, usually studied by applying semi-classical approaches. We discuss how a quantum mechanical relativ…

Quenching of quantum Hall effect and the role of undoped planes in multilayered epitaxial graphene

We propose a mechanism for the quenching of the Shubnikov de Haas oscillations and the quantum Hall effect observed in epitaxial graphene. Experimental data show that the scattering time of the conduction electron is magnetic field dependent and of the order of the cyclotron orbit period, \textit{i.e.} can be much smaller than the zero field scattering time. Our scenario involves the extraordinary graphene $n=0$ Landau level of the uncharged layers that produces a high density of states at the Fermi level. We find that the coupling between this $n=0$ Landau level and the conducting states of t…

Quenching of the Quantum Hall Effect in PbTe Wide Parabolic Quantum Wells

We show that for the case of a many valley host semiconductor an edge channel (EC) related non-local behaviour can persist also in the 3D-regime where the quantum Hall effect (QHE) is already quenched. We demonstrate that the QHE is replaced by conductance fluctuations due to EC backscattering in the contact arms, which leads to a fluctuating current redistribution between a dissipative bulk electron system and a less-dissipative EC-system. Both electron systems are located in different valleys of the band structure. The linear increase of Rxx with the magnetic field is explained by EC-backsca…

界面调控增强与低温淬灭的轨道霍尔电流在轻金属/镍双层膜中诱导力矩与磁电阻

Interface tuned Enhanced and Low Temperature Quenching of Orbital Hall Currents Induce Torque and magnetoresistance in Light Metal/Nickel Bilayers

该研究探究轻金属/铁磁体双层膜中轨道霍尔效应诱导的电流效应，通过测量Ni/Ti薄膜的二次谐波电压提取OHT效率与UOMR，发现Cu中间层及Ti厚度增加可增强两者，低温会淬灭，揭示体轨道霍尔效应为共同机制。

Quantum spin/valley Hall effect and topological insulator phase transitions in silicene

We present a theoretical realization of quantum spin and quantum valley Hall effects in silicene. We show that combination of an electric field and intrinsic spin-orbit interaction leads to quantum phase transitions at the charge neutrality point. This phase transition from a two dimensional topological insulator to a trivial insulating state is accompanied by a quenching of the quantum spin Hall effect and the onset of a quantum valley Hall effect, providing a tool to experimentally tune the topological state of silicene. In contrast to graphene and other conventional topological insulators, …

Intrinsic Spin and Orbital Hall Effects from Orbital Texture

We show theoretically that both intrinsic spin Hall effect (SHE) and orbital Hall effect (OHE) can arise in centrosymmetric systems through momentum-space orbital texture, which is ubiquitous even in centrosymmetric systems unlike spin texture. OHE occurs even without spin-orbit coupling (SOC) and is converted into SHE through SOC. The resulting spin Hall conductivity is large (comparable to that of Pt) but depends on the SOC strength in a nonmonotonic way. This mechanism is stable against orbital quenching. This work suggests a path for an ongoing search for materials with stronger SHE. It al…