Possible ferrimagnetism and ferroelectricity of half-substituted rare-earth titanate: a first-principles study on Y$_{0.5}$La$_{0.5}$TiO$_3$

TL;DR

This study uses first-principles calculations to explore the potential multiferroic properties of half-substituted YLaTiO3, revealing ferromagnetism and hybrid improper polarization influenced by structural details and disorder.

Contribution

It provides new insights into the magnetic and ferroelectric behaviors of Y$_{0.5}$La$_{0.5}$TiO$_3$ through first-principles analysis, highlighting the role of structural phase competition and disorder.

Findings

Ferromagnetic state with 0.25 μB/Ti is lowest energy.

Hybrid improper polarizations can be significantly affected by magnetism.

Disorder may lead to relaxor behaviors in real materials.

Abstract

Titanates with the perovskite structure, including ferroelectrics (e.g., BaTiO$_3$) and ferromagnetic ones (e.g., YTiO$_3$), are important functional materials. Recent theoretical studies predicted multiferroic states in strained EuTiO$_3$ and titanate superlattices, the former of which has already been experimental confirmed. Here, a first-principles calculation is performed to investigate the structural, magnetic, and electronic properties of Y half-substituted LaTiO3. Our results reveal that the magnetism of Y$_{0.5}$La$_{0.5}$TiO$_3$ sensitively depends on its structural details because of the inherent phase competition. The lowest energy state is the ferromagnetic state, resulting in 0.25 $\mu_{\rm B}$/Ti. Furthermore, some configurations of Y$_{0.5}$La$_{0.5}$TiO$_3$ exhibit hybrid improper polarizations, which can be significantly affected by magnetism, resulting in the multiferroic properties. Because of the quenching disorder of substitution, the real Y$_{0.5}$La$_{0.5}$TiO3 material with random A-site ions may exhibit interesting relaxor behaviors.