Magnetic and Electronic Properties of Spin-Orbit Coupled Dirac Electrons on a $(001)$ Thin Film of Double Perovskite Sr$_2$FeMoO$_6$

TL;DR

This paper models the electronic and magnetic properties of a strained Sr$_2$FeMoO$_6$ thin film, revealing robust ferrimagnetism, Dirac dispersions, and flat bands influenced by strong spin-orbit coupling, with implications for spintronics and flat band physics.

Contribution

It introduces an interacting model capturing the effects of spin-orbit coupling and strain on the magnetic and electronic structure of Sr$_2$FeMoO$_6$ thin films, highlighting emergent Dirac and flat band features.

Findings

Strong spin-orbit coupling induces ferrimagnetism and Dirac dispersions.

Magnetic order persists across a wide doping range.

Potential for flat band physics like Wigner crystallization.

Abstract

We present an interacting model for the electronic and magnetic behavior of a strained $(001)$ atomic layer of Sr$_2$FeMoO$_6,$ which shows room-temperature ferrimagnetism and magnetoresistance with potential spintronics application in the bulk. We find that the strong spin-orbit coupling in the molybdenum 4$d$ shell gives rise to a robust ferrimagnetic state with an emergent spin-polarized electronic structure consisting of flat bands and four massive or massless Dirac dispersions. Based on the spin-wave theory, we demonstrate that the magnetic order remains intact for a wide range of doping, leading to the possibility of exploring flat band physics, such as Wigner crystallization in electron-doped Sr$_{2-x}$La$_{x}$FeMoO$_6.$