We report observation of intrinsic inverse spin Hall effect in un-doped GaAs multiple quantum wells with a sample temperature of 10 K. A transient ballistic pure spin current is injected by a pair of laser pulses through quantum interference. By time-resolving the dynamics of the pure spin current, the momentum relaxation time is deduced, which sets the lower limit of the scattering time between electrons and holes. The transverse charge current generated by the pure spin current via the inverse spin Hall effect is simultaneously resolved. We find that the charge current is generated well before the first electron-hole scattering event. Generation of the transverse current in the scattering-free ballistic transport regime provides unambiguous evidence for the intrinsic inverse spin Hall effect.
Linear magnetization dependence of the intrinsic anomalous Hall effect
从实验和理论上研究了Mn $_5$ Ge $_3$铁磁薄膜的反常霍尔效应。我们分离了对实验反常霍尔效应的本征和非本征贡献，并利用第一性原理方法从布洛赫态的Berry曲率计算了本征反常霍尔电导率.本征反常霍尔电导率线性依赖于磁化强度，这可以从有限温度下自旋取向的长波长波动来理解。理论和实验之间的定量一致性非常好，不仅在0 K附近，而且在有限温度下，高达约240 K（0.8 T $_C$ }）
Detecting the orientation of the Néel vector is a major research topic in antiferromagnetic spintronics. Here we recognize the intrinsic nonlinear Hall effect, which is independent of the relaxation time, as a prominent contribution to the time-reversal-odd second order conductivity and can be used to detect the flipping of the Néel vector. In contrast, the Berry-curvature-dipole-induced nonlinear Hall effect depends linear on relaxation time and is time-reversal-even. We study the intrinsic nonlinear Hall effect in an antiferromagnetic metal: tetragonal CuMnAs, and show that its nonlinear Hal…
The intrinsic anomalous Hall effect is one of the most exciting manifestations of the geometric properties of the electronic wave-function. Here, we predict that the electronic wave-function's geometric nature also gives rise to a purely quantum mechanical, {\it intrinsic} (scattering time-independent) component of the Hall conductivities in the presence of a magnetic field. We show that the orbital magnetic moment and the anomalous Hall velocity combine to generate a scattering time-independent contribution to the Hall effect, in addition to the Lorentz force induced scattering time-dependent…
The measured Hall angle in a ferromagnetic nanomagnet shows a substantial non-linear dependence on an external magnetic field, which cannot be explained by adopted mechanisms of the Ordinary and Anomalous (AHE) Hall effects implying a linear plus constant dependence on the external magnetic field. We suggest that there is an additional non-linear contribution from the Inverse Spin Hall effect (ISHE). The significant contribution of ISHE in a ferromagnet is supported by perfect agreement of experiment with a phenomenological theory of ISHE. We observed different dependencies of AHE and ISHE on …
Valley-related multiple Hall effect in 2D lattice is a fundamental transport phenomenon in the fields of condensed-matter physics and material science. So far, most proposals for its realization are limited to toy models or extrinsic effects. Here, based on tight-binding model and first-principles calculations, we report the discovery of intrinsic valley-related multiple Hall effect in 2D organometallic lattice of NbTa-benzene. Protected by the breaking of both time-reversal and inversion symmetry, NbTa-benzene exhibits large valley polarization spontaneously in both the conduction and valence…
Response properties that are purely intrinsic to physical systems are of paramount importance in physics research, as they probe fundamental properties of band structures and allow quantitative calculation and comparison with experiment. For anomalous Hall transport in magnets, an intrinsic effect can appear at the second order to the applied electric field. We show that this intrinsic second-order anomalous Hall effect is associated with an intrinsic band geometric property -- the dipole moment of Berry-connection polarizability (BCP) in momentum space. The effect has scaling relation and sym…
Maximizing the spin-orbit torque efficiency of Pt/Ti multilayers by optimization of the tradeoff between the intrinsic spin Hall conductivity and carrier lifetime
Charge-spin interconversion in magnetic materials is investigated by using first-principles calculations. In addition to the conventional spin Hall effect (SHE) that requires mutual orthogonality of the charge current, spin-flow direction, and spin polarization, the recently proposed anomalous SHE (ASHE) is confirmed in Mn2Au and WTe2. The interaction of the order parameter with conduction electrons leads to sizeable nonzero spin Berry curvatures that give rise to nonzero anomalous spin Hall conductivity (ASHC). Our calculations show that the ASHE is intrinsic and originates from the order-par…
Orbital enhanced intrinsic nonlinear planar Hall effect for probing topological phase transition in CuTlSe$_{2}$
School of Physics, Beihang University（北京航空航天大学物理学院）；Interdisciplinary Center for Theoretical Physics and Information Sciences (ICTPIS), Fudan University（复旦大学理论物理与信息科学交叉中心）；Peng Huanwu Collaborative Center for Research and Education, Beihang University（北京航空航天大学彭桓武研究院）；Research Laboratory for Quantum Materials, IAPME, University of Macau（澳门大学量子材料研究实验室（IAPME））
Intrinsic quantum anomalous Hall phase induced by proximity in germanene/Cr$_2$Ge$_2$Te$_6$ van der Waals heterostructure
范德华异质结结合内禀磁性和拓扑有序性为实现量子反常霍尔效应开辟了一条新的途径。在这项工作中，我们使用第一性原理计算和有效的模型分析，提出了强大的量子反常霍尔态与相当大的带隙出现在范德华异质结的锗烯/Cr $_2$ Ge $_2$ Te $_6$。这种异质结构具有很高的热力学稳定性，从而有利于其实验制备。此外，我们发现，邻近效应增强了锗烯和Cr $_2$ Ge $_2$ Te $_6$层之间的耦合，诱导非平凡的带隙在很宽的范围从29 meV到72 meV。带隙内的手征边缘状态，导致霍尔电导量子化为$-e^2/h$，是清晰可见的。这一发现为探测量子反常霍尔态和实现高温下非平凡量子输运的进一步应用提供了理想的候选者。
Pure spin current based research is mostly focused on ferromagnet (FM)/heavy metal (HM) system. Because of the high spin orbit coupling (SOC) these HMs exhibit short spin diffusion length and therefore possess challenges for device application. Low SOC (elements of light weight) and large spin diffusion length make the organic semiconductors (OSCs) suitable for future spintronic applications. From theoretical model it is explained that, due to $π$ - $σ$ hybridization the curvature of the C$_{60}$ molecules may increase the SOC strength. Here, we have investigated spin pumping and inverse spin …
In time-reversal invariant systems, all charge Hall effects predicted so far are extrinsic effects due to the dependence on the relaxation time. We explore intrinsic Hall signatures by studying quantum noise spectrum of the Hall current in time-reversal invariant systems, and discover intrinsic thermal Hall noises in both linear and nonlinear regimes. As the band geometric characteristics, quantum geometric tensor and Berry curvature play critical roles in various Hall effects, so are their quantum fluctuations. It is found that the thermal Hall noise in linear order of the electric field is p…
In an easy-plane antiferromagnet with the Dzyaloshinskii-Moriya interaction (DMI), magnons are subject to an effective spin-momentum locking. An in-plane temperature gradient can generate interfacial accumulation of magnons with a specified polarization, realizing the magnon thermal Edelstein effect. We theoretically investigate the injection and detection of this thermally-driven spin polarization in an adjacent heavy metal with strong spin Hall effect. We find that the inverse spin Hall voltage depends monotonically on both temperature and the DMI but non-monotonically on the hard-axis aniso…
We study theoretically and experimentally the spin pumping signals induced by the resonance of canted antiferromagnets with Dzyaloshinskii-Moriya interaction and demonstrate that they can generate easily observable inverse spin-Hall voltages. Using a bilayer of hematite/heavy metal as a model system, we measure at room temperature the antiferromagnetic resonance and an associated inverse spin-Hall voltage, as large as in collinear antiferromagnets. As expected for coherent spin-pumping, we observe that the sign of the inverse spin-Hall voltage provides direct information about the mode handedn…
