Large topological Hall effect in an easy-cone ferromagnet (Cr0.9B0.1)Te

Yangkun He,Gerhard H Fecher,Walter Schnelle,Jacob Gayles,Yu Pan,Claudia Felser,Chenguang Fu,Johannes Kroder

doi:10.1063/5.0018229

Yangkun He, Gerhard H Fecher + Show 6 more

Open Access

https://doi.org/10.1063/5.0018229

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Abstract

The Berry phase understanding of electronic properties has attracted special interest in condensed matter physics, leading to phenomena such as the anomalous Hall effect and the topological Hall effect. A non-vanishing Berry phase, induced in momentum space by the band structure or in real space by a non-coplanar spin structure, is the origin of both effects. Here, we report a sign conversion of the anomalous Hall effect and a large topological Hall effect in (Cr0.9B0.1)Te single crystals. The spin reorientation from an easy-axis structure at high temperature to an easy-cone structure below 140 K leads to conversion of the Berry curvature, which influences both, anomalous and topological, Hall effects in the presence of an applied magnetic field and current. We compare and summarize the topological Hall effect in four categories with different mechanisms and have a discussion into the possible artificial fake effect of the topological Hall effect in polycrystalline samples, which provides a deep understanding of the relation between the spin structure and Hall properties.

Highlights

A real-space Berry phase originating from non-coplanar spin texture or magnetic topological excitations like skyrmions9 with non-zero scalar spin chirality can play the role of the magnetic field and contribute to the Hall signal, referred to as the topological Hall effect (THE)
Hall effect was observed in systems with a non-coplanar antiferromagnetic spin structure, such as Mn5Si3,16 MnP,17 and YMn6Sn6.18 Under an applied magnetic field strong enough for a metamagnetic or spin-flop transition, the antiferromagnetic coupled or canted spins align to the field direction due to the Zeeman energy, a process during which a large topological Hall resistivity of up to 10À1 lX cm has been observed
When the applied field direction is along the c-axis, the anomalous Hall resistivity qAHE is positive at high temperature with a collinear spin structure

Summary

Introduction

The latter is due to relativistic effects such as the spin–orbit interaction but can be induced by a non-collinear magnetic spin texture.5,6 The combination of these phenomena leads to the momentum-space Berry curvature as a linear response to an applied electric field.7,8 a real-space Berry phase originating from non-coplanar spin texture or magnetic topological excitations like skyrmions9 with non-zero scalar spin chirality can play the role of the magnetic field and contribute to the Hall signal, referred to as the topological Hall effect (THE).10. The spin reorientation from an easy-axis structure at high temperature to an easy-cone structure below 140 K leads to conversion of the Berry curvature, which influences both, anomalous and topological, Hall effects in the presence of an applied magnetic field and current.

Results

Conclusion