Modulation of magnetic property of double-perovskite La2MnCoO6 films by controlling B-antisite disorder

TL;DR

This study investigates how controlling B-antisite disorder in La2MnCoO6 films affects their magnetic properties, revealing a linear decrease in magnetization with increased disorder and proposing a local-spin-moment model for understanding these effects.

Contribution

It provides a quantitative analysis of B-antisite disorder effects on magnetic and electronic states in La2MnCoO6 films, introducing a local-spin-moment model to explain the observed phenomena.

Findings

Magnetization decreases linearly with increasing antisite disorder.

Valence states of Mn and Co remain unchanged regardless of disorder.

Rearrangement of Co local spin moments is key to tuning magnetism.

Abstract

The predicted physical properties of double perovskites have usually been compromised by their intrinsic B-antisite (AS) disorder effect, but the relationship between them is still unclear for the La2MnCoO6 (LMCO) system. This study focuses on controlling the AS disorder and quantitatively reveals correlations with magnetic and electronic states in epitaxial LMCO films grown on (111) SrTiO3 substrates. The AS fraction was precisely controlled by tuning the growth conditions as evaluated from saturation magnetization and x-ray reflection profiles. The saturation magnetization at 5 K decreased linearly from 6 uB per formula unit by 50% as the AS fraction increased from 0 (perfectly ordered) to 0.5 (fully disordered). The x-ray absorption spectroscopy revealed that valence states of Mn and Co were 4+ (3d^3) and 2+ (3d^7), respectively, regardless of AS fraction. A local-spin-moment model is proposed to explain the net magnetizations with and without AS disorder and Mn/Co valence states, suggesting that only the rearrangement of local spin moment of Co at the antisite plays a key role in tuning the magnetism in this LMCO system.