Coupled structural distortions, domains, and control of phase competition in polar SmBaMn$_2$O$_6$

TL;DR

This study uses theoretical and computational methods to analyze how coupled structural distortions influence the electronic and magnetic phases of SmBaMn$_2$O$_6$, revealing ways to control these phases via structural domain engineering.

Contribution

It introduces a framework combining group theory and first-principles calculations to understand and manipulate phase competition in complex polar materials.

Findings

Structural distortions stabilize the ground state and domain wall vortices.

Crystal structure can be used to control electronic and magnetic phases.

Insights into multiscale physics of SmBaMn$_2$O$_6$ and similar materials.

Abstract

Materials with coupled or competing order parameters display highly tunable ground states, where subtle perturbations reveal distinct electronic and magnetic phases. These phases generally are underpinned by complex crystal structures, but the role of structural complexity in these phases often is unclear. We use group theoretic methods and first-principles calculations to analyze a set of coupled structural distortions that underlie the polar charge- and orbitally- ordered antiferromagnetic ground state of $A$-site ordered SmBaMn$_2$O$_6$. We show that these distortions play a key role in establishing the ground state and stabilizing a network of domain wall vortices. Furthermore, we show that the crystal structure provides a knob to control competing electronic and magnetic phases at structural domain walls and in epitaxially strained thin films. These results provide new understanding of the complex physics realized across multiple length scales in SmBaMn$_2$O$_6$ and demonstrate a framework for systematic exploration of correlated and structurally complex materials.