# Interplay of Dirac electrons and magnetism in AMnBi2 (A=Ca, Sr)

## TL;DR

This study investigates how Dirac electrons interact with magnetic properties in AMnBi2 compounds, revealing enhanced exchange coupling and charge-gap opening, which advances understanding of magnetic Dirac materials and their potential applications.

## Contribution

First detailed analysis of exchange energies in magnetic Dirac materials, showing how Dirac layers influence magnetic interactions and charge-gap formation.

## Key findings

- Dirac layers significantly enhance magnetic exchange coupling.
- Charge-gap opens along the Dirac locus due to magnetic interactions.
- Magnetic Dirac materials offer a platform for spin-Fermion physics and device applications.

## Abstract

Dirac materials exhibit intriguing low-energy carrier dynamics that offer a fertile ground for novel physics discovery. Of particular interest is the interplay of Dirac carriers with other quantum phenomena, such as magnetism. Here we report on a two-magnon Raman scattering study of AMnBi2 (A=Ca, Sr), a prototypical magnetic Dirac system comprising alternating Dirac-carrier and magnetic layers. We present the first accurate determination of the exchange energies in these compounds and, by comparison to the reference compound BaMn2Bi2, we show that the Dirac-carrier layers in AMnBi2 significantly enhance the exchange coupling between the magnetic layers, which in turn drives a charge-gap opening along the Dirac locus. Our findings break new grounds in unveiling the fundamental physics of magnetic Dirac materials, which offer a novel platform for probing a distinct type of spin-Fermion interaction. The outstanding properties of these materials allow a delicate manipulation of the interaction between the Dirac carriers and magnetic moments, thus holding great promise for applications in magnetic Dirac devices.

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Source: https://tomesphere.com/paper/1703.02712