Compensated magnetism by design in double perovskite oxides

TL;DR

This paper uses advanced computational methods to identify and predict double perovskite oxides that exhibit compensated half-metallic antiferromagnetism with near-zero net magnetic moment, considering complex interactions like spin-orbit coupling.

Contribution

It introduces a comprehensive approach including structural relaxation and spin-orbit effects to predict new compensated half-metallic antiferromagnets in oxide double perovskites.

Findings

K$_2$MnRhO$_6$ and La$_2$CrWO$_6$ are identified as promising candidates.

Orbital moments can be tuned to compensate spin-orbit effects.

Predicted materials may be synthesized via layer-by-layer oxide deposition.

Abstract

Taking into account Goodenough's superexchange rules, including both full structural relaxation and spin-orbit coupling, and checking strong correlation effects, we look for compensated half metals within the class of oxide double perovskites materials. Identifying likely half metallic (or half semimetallic) antiferromagnets, the full complications including orbital magnetism are included in order to arrive at realistic predictions of designed magnetic compounds with (near) vanishing net moment. After sorting through several candidates that have not been considered previously, two materials, K$_2$MnRhO$_6$ and La$_2$CrWO$_6$, remain as viable candidates. An important factor is obtaining compounds either with very small induced orbital moment (helped by closed subshells) or with an orbital moment that compensates the spin-orbit driven degradation of half metallic character. While thermodynamic stability of these materials cannot be ensured, the development of layer-by-layer oxide deposition techniques does not require that materials be thermodynamically stable to be synthesized.