Side-jump Effect Research Articles

Photon self-energy in a magnetized chiral plasma from kinetic theory

We study the photon self-energy in magnetized chiral plasma by solving the response of electromagnetic field perturbations in chiral kinetic theory with Landau level states. With lowest Landau level approximation and in collisionless limit, we find solutions for three particular perturbations: parallel electric field, static perpendicular electric and magnetic field, corresponding to chiral magnetic wave, drift state and tilted state, from which we extract components of photon self-energy in different kinematics. We show no solution is possible for more general field perturbations. We argue this is an artifact of the collisionless limit: while static solution corresponding to drift state and tilted state can be found, they cannot be realized dynamically without interaction between Landau levels. We also discuss possible manifestation of side-jump effect due to both boost and rotation, with the latter due to the presence of background magnetic field.

Anomalous Hall effect in magnetic topological insulators: Semiclassical framework

The anomalous Hall effect (AHE) is studied on the surface of a 3D magnetic topological insulator. By applying a modified semiclassical framework, all three contributions to the AHE, the Berry curvature effect, the side-jump effect and the skew scattering effects are systematically treated, and analytical expressions for the conductivities are obtained in terms of the Fermi level, the spatial orientation of the surface magnetization and the concentration of magnetic and nonmagnetic impurities. We demonstrate that the AHE can change sign by altering the orientation of the surface magnetization, the concentration of the impurities and also the position of the Fermi level, in agreement with recent experimental observations. We show how each contribution to the AHE, or even the whole AHE, can be turned off by properly adjusting the given parameters. For example, one can turn off the anomalous hall conductivity in a system with in-plane magnetization by pushing the system into the fully metallic regime.

Magneto-transport in a chiral fluid from kinetic theory

We argue that in order to study the magneto-transport in a relativistic Weyl fluid, it is needed to take into account the associated quantum corrections, namely the side-jump effect, at least to second order. To this end, we impose Lorentz invariance to a system of free Weyl fermions in the presence of the magnetic field and find the second order correction to the energy dispersion. By developing a scheme to compute the integrals in the phase space, we show that the mentioned correction has non-trivial effects on the thermodynamics of the system. Specifically, we compute the expression of the negative magnetoresistivity in the system from the enthalpy density in equilibrium. Then in analogy with Weyl semimetal, in the framework of the chiral kinetic theory and under the relaxation time approximation, we explicitly compute the magneto-conductivities, at low temperature limit (T ≪ μ). We show that the conductivities obey a set of Ward identities which follow from the generating functional including the Chern-Simons part.

Boost invariant formulation of the chiral kinetic theory

We formulate the chiral kinetic equation with the longitudinal boost invariance. We particularly focus on the physical interpretation of the particle number conservation. There appear two terms associated with the expansion, which did not exist in the non-chiral kinetic equation. One is a contribution to the transverse current arising from the side-jump effect, and the other is a change in the density whose flow makes the longitudinal current. We point out a characteristic pattern in the transverse current driven by the expansion, which we call the chiral circular displacement.

How disorder affects the Berry-phase anomalous Hall conductivity: A reciprocal-space analysis

The anomalous Hall conductivity of "dirty" ferromagnetic metals is dominated by a Berry-phase contribution which is usually interpreted as an intrinsic property of the Bloch electrons in the pristine crystal. In this work we evaluate the geometric Hall current directly from the electronic ground state with disorder, and then recast it as an integral over the crystalline Brillouin zone. The integrand is a generalized k-space Berry curvature, obtained by unfolding the Berry curvature from the small Brillouin zone of a large supercell. Therein, disorder yields a net extrinsic Hall contribution, which we argue is related to the elusive side-jump effect. As an example, we unfold the first-principles Berry curvature of an Fe3Co ordered alloy from the original fcc-lattice Brillouin zone onto a bcc-lattice zone with four times the volume. Comparison with the virtual-crystal Berry curvature clearly reveals the symmetry-breaking effects of the substitutional Co atoms.

Structure, magnetic and electrical transport properties of cosputtered Fe 0.5Ge 0.5 nanocomposite films

Fe 0.5Ge 0.5 nanocomposite films with different film thicknesses were fabricated using cosputtering. The films are composed of Ge, Fe and Fe 3Ge 2, and are ferromagnetic at room temperature. The saturation magnetization and magnetic interaction including dipolar interaction and exchange coupling increase with the increasing film thickness. The electrical conductance mechanism turns from metallic to semiconducting and the saturation Hall resistivity ρ xys increases with the decreasing film thickness. At 28 nm, ρ xys is ∼137 μΩ cm at 2 K, about 150 times larger than that of pure Fe film (0.9 μΩ cm) and four orders larger than that of bulk Fe. The ρ xy – H curves of all the films show the same linearity character in low-field range even though the temperature-independent slope is different at different film thicknesses. At high temperatures, the skew scattering mechanism is dominant. At low temperatures, side-jump effect should be dominant at large resistivity ρ xx regime for the thin films, and the skew scattering is dominant at small ρ xx regime for the thick films.

Spin-dependent Hall effect in semiconductor quantum wells

We present a theoretical study of the spin-dependent scattering of electrons from screened attractive and repulsive impurities in III-V semiconductor quantum wells. The effective one-band Hamiltonian and the Rashba spin–orbit interaction are used. We demonstrated that the asymmetry of the spin-dependent skew-scattering and side-jump effect can lead to a quite large spin-dependent (anomalous) Hall effect at zero magnetic field in all-semiconductor quantum well structures. Our theory predicts a measurable spin-dependent Hall angle that reaches about 2.5×10−3 rad for a CdTe/InSb/CdTe quantum well with impurities doped in the center of the well.

Free-electron-like Hall effect and deviations from free-electron behavior in Ca-Al amorphous alloys.

The Hall coefficients of Ca-Al amorphous alloys have been measured at 4.2 K over a wide range of compositions. It is shown that the magnitude of the Hall coefficients are close to the nearly-free-electron (NFE) prediction for low Ca concentrations but deviate significantly from the NFE values for Ca concentration greater than 45 at. %. The deviations from the free-electron values have previously been attributed to the effects of s-d hybridization, while a reduction in magnitude by Au doping has been argued to result from the side-jump effect.

Side-jump effect in paramagnetic amorphous metals.

A systematic study of the resistivity (\ensuremath{\rho}), the Hall coefficients (${\mathit{R}}_{\mathit{H}}$), and the magnetic susceptibilities (\ensuremath{\chi}) of the Zr-based paramagnetic amorphous alloys suggests a self-consistent explanation for the frequently observed positive values of ${\mathit{R}}_{\mathit{H}}$ that is based on the side-jump effect. Measurements for \ensuremath{\chi}, ${\mathit{R}}_{\mathit{H}}$, and \ensuremath{\rho} of (${\mathrm{Zr}}_{0.64}$${\mathrm{Cu}}_{0.36}$${)}_{1\mathrm{\ensuremath{-}}\mathit{x}}$${\mathrm{Al}}_{\mathit{x}}$ and \ensuremath{\chi} for (${\mathrm{Zr}}_{0.50}$${\mathrm{Ni}}_{0.50}$${)}_{1\mathrm{\ensuremath{-}}\mathit{x}}$${\mathrm{Al}}_{\mathit{x}}$ alloys are presented. The odd behavior of the Hall coefficients of these alloys and the anomalous positive Hall coefficients of paramagnetic Zr-based amorphous alloys can be accounted for in terms of the enhanced spin-orbit interaction, which produces the side-jump effect.

THE HALL EFFECT IN KONDO SYSTEMS

THE HALL EFFECT IN KONDO SYSTEMS

Positive Hall effect in paramagnetic amorphous Zr-Fe.

We present measurements and analysis of the Hall effect in amorphous paramagnetic Zr-Fe. From the correlation between the Hall coefficient and the valence susceptibility we show that the Hall effect is dominated by an anomalous contribution due to the side-jump effect, the first time such a contribution has been clearly identified in an amorphous paramagnetic system. We propose that the anomalous contribution accounts for the positive value of the Hall coefficient seen in many amorphous alloys.

Extraordinary Hall-effect in ferromagnetic (rare-earth)Al2

The extraordinary Hall effect of ferromagnetic metals is ascribed to the asymmetric scattering of the conduction electrons through two basic mechanisms, namely the skew-scattering effect and the side-jump effect. For the pure rare-earth metals the explanation of these effects was first given from the Coulomb interaction between conduction electrons and localized $4f$ electrons. We present here Hall-effect measurements on some intermetallic compounds of the form $R{\mathrm{Al}}_{2}$ ($R=\mathrm{P}\mathrm{r},\phantom{\rule{0ex}{0ex}}\mathrm{N}\mathrm{d},\phantom{\rule{0ex}{0ex}}\mathrm{G}\mathrm{d},\phantom{\rule{0ex}{0ex}}\mathrm{a}\mathrm{n}\mathrm{d}\phantom{\rule{0ex}{0ex}}\mathrm{T}\mathrm{b}$). The same qualitative features previously observed for the rare earths are also found. However the Coulomb interaction alone fails to give an extraordinary Hall effect in the case of ferromagnets like Gd and Gd${\mathrm{Al}}_{2}$ where there is an $S$-state magnetic ion and the other possible sources in the formation of the effect, particularly covalent mixing interaction and intrinsic spin-orbit coupling of the conduction band, are briefly considered.