Weak localization in systems with chiral spin textures and skyrmion crystals

Abstract

Theory of interference-induced quantum corrections to conductivity is developed for twodimensional systems with chiral spin textures including skyrmions. The effect of exchange interaction between electrons and spin textures on weak localization of electronic waves is studied. The spin dephasing rates are calculated as functions of the spin texture size. The anomalous magnetoresistance is shown to be governed by the size and magnetization spatial distribution of the spin textures. The effect of average magnetization-induced spin splitting on weak localization is analyzed. The sign-alternating weak-antilocalization magnetoresistance is demonstrated for skyrmion crystals. We argue that analysis of the low-field magnetoresistance serves as an independent tool for an experimental detection of chiral spin textures and, in particular, skyrmions.

Topological Hall Effect in Traditional Ferromagnet Embedded with Black-Phosphorus-Like Bismuth Nanosheets

“…Furthermore, the magnetic texture of skyrmions is also a new scattering source for carriers, accounting for the magnetoresistivity hump near H c in Figure 4. 37,38 To the best of our knowledge, it is the first time in the literature to observe all these skyrmion-induced features, for example, THE, magnetoresistivity anomaly and differential magnetic susceptibility plateau, simultaneously in the same system. From our experimental data, we can also estimate the average skyrmion size is about 14 nm (see SI Section S-X), comparable with the lateral sizes of Bi nanosheets which may vary from 10 to 100 nm (see Figure 1b).…”

Soft-Magnetic Skyrmions Induced by Surface-State Coupling in an Intrinsic Ferromagnetic Topological Insulator Sandwich Structure

“…This would be because LMR is quantum transport effect and in this temperature range quantum coherence length is too short to observe. As the THE hump-like curves disappear around T = 7 K and this is close to T * , the negative MR can be considered as the scattering induced by skyrmions 43 . As explained in the main text and Methods, we numerically calculated the energy stability of three types of skyrmions (Bloch, Néel 1 and Néel 2 types) in the BST/MnBST/BST/MnBST structure.…”

Coherent backscattering in the topological Hall effect

“…One can find a weak dependence of correction to topological Hall effect ratio with electron density in equation (53), which is ∝ ℏ ϵFτ with ϵ F = πℏ 2 ne m . n e is the electron density and m is the effective mass of carrier.…”

“…In this context, the effect on weak localization of inhomogeneous magnetic structures in real space has received almost no attention, despite the inexorable rise of magnetic systems with topological spin textures such as skyrmions. One notable exception is a recent study of weak localization in longitudinal transport due to scattering off chiral spin textures [53]. To date no studies have considered weak localization in the Hall conductivity of topological spin textures, presumably because the effect is expected to vanish in ordinary Hall transport [54], though it is believed to play a part in the anomalous Hall effect [55].…”

“…We show that the topological Hall effect is a manifestation of inter-band quantum coherence induced by a real-space magnetic texture [56], and accounting for the interplay between diagonal and off-diagonal density matrix response is vital in order to capture the underlying physics and determine the correct result both in the Born approximation and for coherent backscattering. We restrict ourselves to scalar impurity scattering, noting that spin-flip scattering can straightforwardly be included along the lines of [53]. This however will only increase the complexity of the theory by modifying the Cooperon quantitatively without bringing about any qualitative changes in our results.…”