Skyrmion Lattice Topological Hall Effect near Room Temperature

Maxime Leroux,Song Jin,Boris Maiorov,Charles Reichhardt,Matthew J. Stolt,Douglas V. Pete

doi:10.1038/s41598-018-33560-2

Abstract

Magnetic skyrmions are stable nanosized spin structures that can be displaced at low electrical current densities. Because of these properties, they have been proposed as building blocks of future electronic devices with unprecedentedly high information density and low energy consumption. The electrical detection of an ordered skyrmion lattice via the Topological Hall Effect (THE) in a bulk crystal, has so far been demonstrated only at cryogenic temperatures in the MnSi family of compounds. Here, we report the observation of a skyrmion lattice Topological Hall Effect near room temperature (276 K) in a mesoscopic lamella carved from a bulk crystal of FeGe. This region coincides with the skyrmion lattice location revealed by neutron scattering. We provide clear evidence of a re-entrant helicoid magnetic phase adjacent to the skyrmion phase, and discuss the large THE amplitude (5 nΩ.cm) in view of the ordinary Hall Effect.

Highlights

Magnetic skyrmions are nanometre size quasi-particles with a whirling spin configuration, which hold great potential as information carriers for electronic devices[1,2,3,4,5]
We report the first observation of a skyrmion Topological Hall Effect (THE) emerging from an ordered skyrmion lattice in a bulk crystal since the original skyrmion THE discovery in the MnSi family of compounds
Using high resolution Hall Effect measurements in a mesoscopic FIB lamella extracted from a single crystal of FeGe, we observe a 5 nΩ.cm THE in a region of field and temperature close to TN where a skyrmion lattice has been observed in bulk samples using SANS42

Summary

Introduction

Magnetic skyrmions are nanometre size quasi-particles with a whirling spin configuration, which hold great potential as information carriers for electronic devices[1,2,3,4,5]. A key advantage of magnetic skyrmions as stable nano-objects is that they can be displaced using relatively low electrical currents[3,17,18] This low critical current for depinning stems from the relative insensitivity of skyrmions to disorder due to the strong Magnus force contribution to the skyrmion dynamics that allows skyrmions to bypass defects[1,4,5,19]. In macroscopic bulk crystals, the skyrmion THE has been detected and correlated with skyrmions imaging, but only in the MnSi family of compounds at cryogenic temperatures[18,22,23,24] This THE originates from electrons accumulating a Berry phase as they travel through skyrmions spin configuration, which acts as an effective magnetic field (Beff ). Electrical manipulation of skyrmions in multilayers[31,32,33,34,35,36] still requires current densities comparable to those required to move domain walls in racetrack type memories[2,3], which is orders of magnitude larger than the current densities required to move skyrmions in clean single crystals[17,18,37]

Methods

Results

Conclusion