scholarly journals The family of topological Hall effects for electrons in skyrmion crystals

2018 ◽  
Vol 91 (8) ◽  
Author(s):  
Börge Göbel ◽  
Alexander Mook ◽  
Jürgen Henk ◽  
Ingrid Mertig
Keyword(s):  
Magnetic Field ◽  
External Magnetic Field ◽  
Hall Effect ◽  
Electron Spin ◽  
Anomalous Hall Effect ◽  
Transverse Spin ◽  
Edge States ◽  
Finite Sample ◽  
Magnetic Texture ◽  
Hall Effects

Abstract Hall effects of electrons can be produced by an external magnetic field, spin–orbit coupling or a topologically non-trivial spin texture. The topological Hall effect (THE) – caused by the latter – is commonly observed in magnetic skyrmion crystals. Here, we show analogies of the THE to the conventional Hall effect (HE), the anomalous Hall effect (AHE), and the spin Hall effect (SHE). In the limit of strong coupling between conduction electron spins and the local magnetic texture the THE can be described by means of a fictitious, “emergent” magnetic field. In this sense the THE can be mapped onto the HE caused by an external magnetic field. Due to complete alignment of electron spin and magnetic texture, the transverse charge conductivity is linked to a transverse spin conductivity. They are disconnected for weak coupling of electron spin and magnetic texture; the THE is then related to the AHE. The topological equivalent to the SHE can be found in antiferromagnetic skyrmion crystals. We substantiate our claims by calculations of the edge states for a finite sample. These states reveal in which situation the topological analogue to a quantized HE, quantized AHE, and quantized SHE can be found.

scholarly journals Landau quantisation of photonic spin Hall effect in monolayer black phosphorus

Nanophotonics ◽  
2019 ◽  
Vol 9 (1) ◽  
pp. 225-233 ◽  
Author(s):  
Guangyi Jia ◽  
Geng Li ◽  
Yan Zhou ◽  
Xianglong Miao ◽  
Xiaoying Zhou
Keyword(s):  
Magnetic Field ◽  
External Magnetic Field ◽  
Hall Effect ◽  
Oscillation Period ◽  
Black Phosphorus ◽  
Spin Hall Effect ◽  
Transverse Spin ◽  
Strong Impact ◽  
Incident Wavelength ◽  
The Rich

AbstractThe photonic spin Hall effect (PSHE) is a promising candidate for controlling the spin states of photons and exploiting next-generation photonic devices based on spinoptics. Herein, the influences of a perpendicular magnetic field on the PSHE appearing on the surface of monolayer black phosphorus (BP) are investigated. Results reveal that both the in-plane and transverse spin-dependent shifts are quantised and show an oscillating pattern due to the splitting of Landau levels (LLs) induced by the external magnetic field B. And the oscillation period of spin Hall shifts gradually increases with strengthening B because of the increase of LL spacings. By contrast, for a fixed magnetic field, as the LL spacings become smaller and smaller with increasing the LL index, the oscillation period of spin Hall shifts gradually decreases as the photonic energy increases. Moreover, it is possibly due to the synergistic role of intrinsic anisotropy, high crystallinity, and quantisation-incurred localised decreases in beating-like complex conductivities of the BP film, giant spin Hall shifts, hundreds of times of the incident wavelength, are obtained in both transverse and in-plane directions. These unambiguously confirm the strong impact of the external magnetic field on the PSHE and shed important insights into understanding the rich magneto-optical transport properties in anisotropic two-dimensional atomic crystals.

scholarly journals Fully spin-polarized quadratic non-Dirac bands realized quantum anomalous Hall effect

2020 ◽  
Vol 22 (2) ◽  
pp. 549-555 ◽  
Author(s):  
Ping Li ◽  
Tian-Yi Cai
Keyword(s):  
Magnetic Field ◽  
Hall Effect ◽  
Quantum State ◽  
Anomalous Hall Effect ◽  
Edge States ◽  
Quantum Anomalous Hall Effect ◽  
Spin Polarized

The quantum anomalous Hall effect is an intriguing quantum state that exhibits chiral edge states in the absence of a magnetic field.

Sign reversal of anomalous Hall effect derived from the transformation of scattering effect in cluster-assembled Ni0.8Fe0.2 nanostructural films

Nanoscale ◽  
2021 ◽  
Author(s):  
Ning Jiang ◽  
Bo Yang ◽  
Yulong Bai ◽  
Yaoxiang Jiang ◽  
Shifeng Zhao
Keyword(s):  
Hall Effect ◽  
Anomalous Hall Effect ◽  
Sign Reversal ◽  
Surface And Interface ◽  
Scattering Effect ◽  
Single Substance ◽  
Interface Scattering ◽  
Hall Effects

Both surface and interface scattering induced a sign reversal of anomalous Hall effects (AHE) in a few heterostructures. The sign reversal exiting in a single-substance can clarify the role of...

Quantum Hall effects

Quantum 20/20 ◽  
2019 ◽  
pp. 303-322
Author(s):  
Ian R. Kenyon
Keyword(s):  
Magnetic Field ◽  
Hall Effect ◽  
Energy Gap ◽  
Quantum Hall ◽  
Free Electrons ◽  
Electron Gases ◽  
Hall Conductance ◽  
Hall Effects ◽  
The Stability ◽  
The Magnetic Field

It is explained how plateaux are seen in the Hall conductance of two dimensional electron gases, at cryogenic temperatures, when the magnetic field is scanned from zero to ~10T. On a Hall plateau σ‎xy = ne 2/h, where n is integral, while the longitudinal conductance vanishes. This is the integral quantum Hall effect. Free electrons in such devices are shown to occupy quantized Landau levels, analogous to classical cyclotron orbits. The stability of the IQHE is shown to be associated with a mobility gap rather than an energy gap. The analysis showing the topological origin of the IQHE is reproduced. Next the fractional QHE is described: Laughlin’s explanation in terms of an IQHE of quasiparticles is presented. In the absence of any magnetic field, the quantum spin Hall effect is observed, and described here. Time reversal invariance and Kramer pairs are seen to be underlying requirements. It’s topological origin is outlined.

Anomalous Hall Effect–Like Behavior with In‐Plane Magnetic Field in Noncollinear Antiferromagnetic Mn 3 Sn Films

2019 ◽  
pp. 1800818 ◽  
Author(s):  
Yunfeng You ◽  
Xianzhe Chen ◽  
Xiaofeng Zhou ◽  
Youdi Gu ◽  
Ruiqi Zhang ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Hall Effect ◽  
Anomalous Hall Effect

The Impurity Spin-Dependent Scattering Effects in the Transport and Spin Resonance of Conduction Electrons in Bismuth Doped Silicon

2015 ◽  
Vol 242 ◽  
pp. 327-331 ◽  
Author(s):  
Andrey V. Soukhorukov ◽  
Davud V. Guseinov ◽  
Alexei V. Kudrin ◽  
Sergey A. Popkov ◽  
Alexandra P. Detochenko ◽  
...  
Keyword(s):  
Hall Effect ◽  
Spin Relaxation ◽  
Electron Spin ◽  
Anomalous Hall Effect ◽  
Hall Resistance ◽  
Resonance Spectroscopy ◽  
Electron Spin Relaxation ◽  
Conduction Electrons ◽  
Spin Resonance ◽  
Hall Effect Measurements

Transport and spin relaxation characteristics of the conduction electrons in silicon samples doped with bismuth in the 1.1·1013- 7.7·1015cm-3concentration range were studied by the Hall and electron spin resonance spectroscopy. Hall effect measurements in the temperature range 10-80 K showed a deviation from the linear dependence of the Hall resistance in the magnetic field, which is a manifestation of the anomalous Hall effect. The magnetoresistance investigation shows that with current increasing magnetoresistance may change its sign from positive to negative, which is most clearly seen when the bismuth concentration goes up to 7.7·1015cm-3. The conduction electron spin relaxation rate dramatically increases in silicon samples with sufficiently low concentration of bismuth ~ 2·1014cm-3. All these results can be explained in terms of the concept of spin-dependent and spin flip scattering induced by heavy bismuth impurity centers.

scholarly journals Large discrete jumps observed in the transition between Chern states in a ferromagnetic topological insulator

2016 ◽  
Vol 2 (7) ◽  
pp. e1600167 ◽  
Author(s):  
Minhao Liu ◽  
Wudi Wang ◽  
Anthony R. Richardella ◽  
Abhinav Kandala ◽  
Jian Li ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Metastable State ◽  
Large Fraction ◽  
Surface States ◽  
Anomalous Hall Effect ◽  
Escape Rate ◽  
Zero Magnetic Field ◽  
Hall Resistance ◽  
Edge States ◽  
Longitudinal Resistance

A striking prediction in topological insulators is the appearance of the quantized Hall resistance when the surface states are magnetized. The surface Dirac states become gapped everywhere on the surface, but chiral edge states remain on the edges. In an applied current, the edge states produce a quantized Hall resistance that equals the Chern numberC= ±1 (in natural units), even in zero magnetic field. This quantum anomalous Hall effect was observed by Changet al. With reversal of the magnetic field, the system is trapped in a metastable state because of magnetic anisotropy. We investigate how the system escapes the metastable state at low temperatures (10 to 200 mK). When the dissipation (measured by the longitudinal resistance) is ultralow, we find that the system escapes by making a few very rapid transitions, as detected by large jumps in the Hall and longitudinal resistances. Using the field at which the initial jump occurs to estimate the escape rate, we find that raising the temperature strongly suppresses the rate. From a detailed map of the resistance versus gate voltage and temperature, we show that dissipation strongly affects the escape rate. We compare the observations with dissipative quantum tunneling predictions. In the ultralow dissipation regime, two temperature scales (T1~ 70 mK andT2~ 145 mK) exist, between which jumps can be observed. The jumps display a spatial correlation that extends over a large fraction of the sample.

Sign in / Sign up

Export Citation Format

Share Document