Field-induced metal-to-insulator transition and colossal anisotropic magnetoresistance in a nearly Dirac material EuMnSb2

Z L Sun,Z F Wang,H M Mu,H H Wang,T Wu,Z Y Wang,X H Chen,X Y Zhou,A F Wang

doi:10.1038/s41535-021-00397-4

Abstract

Realizing applicably appreciated spintronic functionalities basing on the coupling between charge and spin degrees of freedom is still a challenge. For example, the anisotropic magnetoresistance (AMR) effect can be utilized to read out the information stored in magnetic structures. However, the application of AMR in antiferromagnet-based spintronics is usually hindered by the small AMR value. Here, we discover a colossal AMR with its value reaching 1.84 × 106% at 2 K, which stems from the field-induced metal-to-insulator transition (MIT), in a nearly Dirac material EuMnSb2. Density functional theory calculations identify a Dirac-like band around the Y point that depends strongly on the spin–orbit coupling and dominates the electrical transport. The indirect band gap at the Fermi level evolves with magnetic structure of Eu2+ moments, consequently giving rise to the field-induced MIT and the colossal AMR. Our results suggest that the antiferromagnetic topological materials can serve as a fertile ground for spintronics applications.

Highlights

The manipulation of charge transport by spin degree of freedom in solid-state systems is at the core of spintronics
The band structure calculations find anisotropic band gaps between different spin orientations: 23.3 meV with Eu2+ moments aligned along the a axis and 62.0 meV with Eu2+ moments aligned along the c axis, respectively
The rotating magnetic field from the a axis to the c axis enforces the orientation of the Eu2+ moments, resulting in different band gap values. Such anisotropic band gap combined with corresponding position of Fermi level can result in the colossal Anisotropic magnetoresistance (AMR)

Summary

Introduction

The manipulation of charge transport by spin degree of freedom in solid-state systems is at the core of spintronics. The conventional AMR effect, in which the electronic band structure is dependent on the spin orientation, is mainly associated with the magnetocrystalline anisotropy arising from the relativistic spin–orbit coupling (SOC). In this sense, the SOC-induced anisotropic response of band structure to external magnetic field and the detailed position of the Fermi level determine the AMR in practical antiferromagnets[12,13,14,15]. The magnetic topological materials can potentially generate a large AMR, which has not yet been observed experimentally.

Methods

Results

Conclusion