Magnetic tuning of band topology evidenced by exotic quantum oscillations in the Dirac semimetal EuMnSb$_2$

TL;DR

This study demonstrates how magnetic field-induced changes in EuMnSb$_2$ alter its electronic band topology, evidenced by quantum oscillations and Berry phase shifts, revealing a magnetic control of topological states.

Contribution

It provides experimental and theoretical evidence that magnetic states can tune the band topology in EuMnSb$_2$, a magnetic topological semimetal, through quantum oscillation analysis.

Findings

Observation of exotic quantum oscillations linked to magnetic states.

Identification of a transition from trivial to non-trivial band topology.

Confirmation of magnetic control over topological electronic properties.

Abstract

Interplay between magnetism and electronic band topology is of central current interest in topological matter research. We use quantum oscillations as powerful tool to probe the evolution of band topology in the Dirac semimetal EuMnSb$_2$. The Eu local 4f magnetic moments display different antiferromagnetic states below 25 K and a field-polarized phase above 16 T. Upon cooling from 65 K into the field-polarized state, an exotic temperature dependent shift of oscillation peaks arises, accompanied by the development of non-zero Berry phase and a huge unconventional splitting of the oscillations. Band-structure calculations confirm the change from trivial to non-trivial band topology induced by the ferromagnetic Eu state, classifying EuMnSb$_2$ as unique magnetic topological semimetal.