Spontaneous atomic ordering and magnetism in epitaxially stabilized double perovskites

TL;DR

This study demonstrates that epitaxial stabilization can induce high atomic ordering and ferrimagnetism in La2CrFeO6 and La2VMnO6 double perovskites, which are otherwise disordered in bulk form, revealing new magnetic and electronic properties.

Contribution

The paper shows that epitaxial growth can spontaneously order B-site transition metals in double perovskites, leading to ferrimagnetism and insulating behavior not observed in bulk materials.

Findings

High B-site order (~90%) in LCFO and (~80%) in LVMO due to epitaxial stabilization

Both compounds exhibit ferrimagnetism with ~2 μB saturation magnetization

LCFO and LVMO are insulating with band gaps of 1.6 eV and 0.9 eV, respectively

Abstract

We have studied the atomic ordering of B-site transition metals and magnetic properties in the pulsed-laser deposited films of La2CrFeO6 (LCFO) and La2VMnO6 (LVMO), whose bulk materials are known to be single perovskites with random distribution of the B-site cations. Despite similar ionic characters of constituent transition metals in each compound, the maximum B-site order attained was surprisingly high, ~90% for LCFO and ~80% for LVMO, suggesting a significant role of epitaxial stabilization in the spontaneous ordering process. Magnetization and valence state characterizations revealed that the magnetic ground state of both compounds was coincidently ferrimagnetic with saturation magnetization of ~2myuB per formula unit, unlike those predicted theoretically. In addition, they were found to be insulating with optical band gaps of 1.6 eV and 0.9 eV for LCFO and LVMO, respectively. Our results present a wide opportunity to explore novel magnetic properties of binary transition-metal perovskites upon epitaxial stabilization of the ordered phase.