scholarly journals Large Hall and Nernst responses from thermally induced spin chirality in a spin-trimer ferromagnet

2021 ◽  
Vol 118 (33) ◽  
pp. e2023588118
Author(s):  
Kamil K. Kolincio ◽  
Max Hirschberger ◽  
Jan Masell ◽  
Shang Gao ◽  
Akiko Kikkawa ◽  
...  
Keyword(s):  
Hall Effect ◽  
Thermal Fluctuations ◽  
Hall Conductivity ◽  
Strong Response ◽  
Thermally Induced ◽  
Conduction Electrons ◽  
Lattice State ◽  
Ferromagnetic Ordering ◽  
Ordering Transition ◽  
Fundamental Units

The long-range order of noncoplanar magnetic textures with scalar spin chirality (SSC) can couple to conduction electrons to produce an additional (termed geometrical or topological) Hall effect. One such example is the Hall effect in the skyrmion lattice state with quantized SSC. An alternative route to attain a finite SSC is via the spin canting caused by thermal fluctuations in the vicinity of the ferromagnetic ordering transition. Here, we report that for a highly conducting ferromagnet with a two-dimensional array of spin trimers, the thermally generated SSC can give rise to a gigantic geometrical Hall conductivity even larger than the intrinsic anomalous Hall conductivity of the ground state. We also demonstrate that the SSC induced by thermal fluctuations leads to a strong response in the Nernst effect. A comparison of the sign and magnitude of fluctuation–Nernst and Hall responses in fundamental units indicates the need for a momentum–space picture to model these thermally induced signals.

Chiral bosonic field theories and the quantum Hall effect

2001 ◽  
Vol 79 (9) ◽  
pp. 1121-1131 ◽  
Author(s):  
P Bracken
Keyword(s):  
Hall Effect ◽  
Gauge Transformation ◽  
Quantum Hall Effect ◽  
Quantum Hall ◽  
Equation Of Motion ◽  
Hall Conductivity ◽  
Field Theories ◽  
Bosonic Field ◽  
Chern Simons

The gauge-transformation properties of the actions of certain scalar and Chern–Simons theories are investigated, including contributions from the boundary. By imposing chirality constraints on the fields, these types of theories can be used to describe the quantum Hall effect. It is shown that the corresponding equation of motion for the associated current for the theory generates an anomaly, which can be related directly to the Hall conductivity. PACS Nos.: 73.43, 03.70, 11.10, 11.30R

NONCOMMUTATIVE DESCRIPTION OF SPIN HALL EFFECT

2009 ◽  
Vol 06 (02) ◽  
pp. 343-360 ◽  
Author(s):  
AHMED JELLAL ◽  
RACHID HOUÇA
Keyword(s):  
Magnetic Field ◽  
Quantum Mechanics ◽  
Hall Effect ◽  
High Frequency ◽  
Hall Conductivity ◽  
Spin Hall Effect ◽  
Harmonic Oscillators ◽  
Frequency Regime ◽  
Basic Features ◽  
Noncommutative Plane

We propose an approach based on a generalized quantum mechanics to deal with the basic features of the intrinsic spin Hall effect. This can be done by considering two decoupled harmonic oscillators on the noncommutative plane and evaluating the spin Hall conductivity. Focusing on the high frequency regime, we obtain a diagonalized Hamiltonian. After getting the corresponding spectrum, we show that there is a Hall conductivity without an external magnetic field, which is noncommutativity parameter θ-dependent. This allows us to make contact with the spin Hall effect and also give different interpretations. Fixing θ, one can recover three different approaches dealing with the phenomenon.

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 Current Percolation in Medium with Boundaries under Quantum Hall Effect Conditions

2012 ◽  
Vol 2012 ◽  
pp. 1-6 ◽  
Author(s):  
M. U. Malakeeva ◽  
V. E. Arkhincheev
Keyword(s):  
Finite Number ◽  
Hall Effect ◽  
Quantum Hall Effect ◽  
Hall Current ◽  
Quantum Hall ◽  
Singular Points ◽  
Hall Conductivity

The current percolation has been considered in the medium with boundaries under quantum Hall effect conditions. It has been shown that in that case the effective Hall conductivity has a nonzero value due to percolation of the Hall current through the finite number of singular points (in our model these are corners at the phase joints).

WILSON LOOPS AND NON-ABELIAN STATISTICS IN THE QUANTUM HALL EFFECT

1992 ◽  
Vol 06 (17) ◽  
pp. 2875-2891
Author(s):  
MICHAEL STONE
Keyword(s):  
Hall Effect ◽  
Quantum Hall Effect ◽  
Quantum Hall ◽  
Conductivity Tensor ◽  
Hall Conductivity ◽  
Wilson Loops ◽  
Many Body ◽  
Quantum Numbers ◽  
The Many ◽  
Chern Simons

There is a topological connection between the boundary excitations of a quantum Hall fluid and the quantum numbers of its vortex-like bulk quasi-particles. I use this connection to examine the group properties of vortex excitations in a generalized quantum Hall fluid, and show how the vortex trajectories become Wilson lines interacting via Chern-Simons fields. As a result, I argue that non-abelian statistics, if they exist, should be independent of the detailed properties of the many-body wavefunction and will depend only on the bulk Hall conductivity tensor.

scholarly journals HALL CONDUCTIVITY ESTIMATES FROM MAGNETOTELLURIC SOUNDING DATA

2020 ◽  
Vol 11 (4) ◽  
pp. 817-828
Author(s):  
V. Plotkin ◽  
V. V. Potapov
Keyword(s):  
Hall Effect ◽  
Normal Wave ◽  
Magnetotelluric Sounding ◽  
Hall Conductivity ◽  
Petroleum Reservoir ◽  
Attenuation Coefficients ◽  
Reservoir Rocks ◽  
Phase Velocities ◽  
Left Circular Polarization ◽  
Semiconductor Properties

Many minerals have semiconductor properties. It is known that petroleum reservoir rocks permeated with hydrocarbon fluids can sometimes behave as semiconductors. In the Earth’s magnetic field, the electrical conductivity of such materials becomes anisotropic, and the Hall effect is quite possible in rocks in natural conditions and detectable by magnetotelluric sounding. In the anisotropic medium, the field is subject to normal mode splitting, and its components show different attenuation coefficients and phase velocities. The modes differ due to polarization and rotation of the field vectors (clockwise in one mode, and counterclockwise in another). With account of the Hall effect, responses of the medium can be different when the medium is excited by a single normal wave. To detect the Hall effect in MTS surveys, we use the polarization analysis method and select the spectra of modes with right and left circular polarization. Special experiments were carried out to detect the contribution of the Hall effect during the MTS surveys. This article presents the first estimates of the Hall conductivity for the studied rocks.

MICROMAGNETISM INDUCED BY THE UNPAIRED ELECTRONS IN InSb SINGLE CRYSTAL

2013 ◽  
Vol 27 (27) ◽  
pp. 1350193
Author(s):  
MIN GE ◽  
SHUN TAN ◽  
LI PI ◽  
YUHENG ZHANG
Keyword(s):  
Single Crystal ◽  
Experimental Results ◽  
Spin Orbit Coupling ◽  
Spin Orbit ◽  
Band Theory ◽  
Metallic Behavior ◽  
Conduction Electrons ◽  
Unpaired Electrons ◽  
Ferromagnetic Ordering ◽  
Strong Spin

In this paper, our experimental results demonstrate that the micromagnetism of InSb is determined by J (where J = L+S) instead of S of unpaired electrons due to the strong spin–orbit coupling. The results of macromagnetism show that the magnetism is diamagnetic, which comes from the Lamor moment of localized electrons and Landau diamagnetic moment of conduction electrons. Below 160 K, ferromagnetic ordering of J, which is induced by the interaction between J, also promotes the appearance of metallic behavior which is different from the well-known band theory.

scholarly journals Relation between the spin Hall conductivity and the spin Chern number for Dirac-like systems

2016 ◽  
Vol 13 (01) ◽  
pp. 1550136 ◽  
Author(s):  
Ömer F. Dayi ◽  
Elif Yunt
Keyword(s):  
Hall Effect ◽  
Chern Number ◽  
Hall Conductivity ◽  
Spin Orbit Coupling ◽  
Spin Orbit ◽  
Quantum Level ◽  
Coupling Term ◽  
Physical Systems ◽  
Rashba Spin ◽  
Spin Hall Conductivity

A semiclassical formulation of the spin Hall effect for physical systems satisfying Dirac-like equation is introduced. We demonstrate that the main contribution to the spin Hall conductivity is given by the spin Chern number whether the spin is conserved or not at the quantum level. We illustrated the formulation within the Kane–Mele model of graphene in the absence and in the presence of the Rashba spin-orbit coupling term.

Creep rupture due to thermally induced cracking

2013 ◽  
Vol 1535 ◽  
Author(s):  
Naoki Yoshioka ◽  
Ferenc Kun ◽  
Nobuyasu Ito
Keyword(s):  
Power Law ◽  
Crack Nucleation ◽  
Waiting Times ◽  
System Size ◽  
Thermal Fluctuations ◽  
Average Lifetime ◽  
Thermally Induced ◽  
Thermally Activated ◽  
Structural Entropy ◽  
Stochastic Time Series

ABSTRACTWe study sub-critical fracture driven by thermally activated crack nucleation in the framework of a fiber bundle model. Based on analytic calculations and computer simulations we show that in the presence of stress inhomogeneities, thermally activated cracking results in an anomalous size effect, i.e. the average lifetime of the system decreases as a power law of the system size, where the exponent depends on the external load and on the temperature. We propose a modified form of the Arrhenius law which provides a comprehensive description of the load, temperature, and size dependence of the lifetime of the system. On the micro-level, thermal fluctuations trigger bursts of breaking events which form a stochastic time series as the system evolves towards failure. Numerical and analytical calculations revealed that both the size of bursts and the waiting times between consecutive events have power law distributions, however, the exponents depend on the load and temperature. Analyzing the structural entropy and the location of consecutive bursts we show that in the presence of stress concentration the acceleration of the rupture process close to failure is the consequence of damage localization.

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