Structural, electronic and magnetic properties of Mott insulating Y1-xLaxTiO3 from hybrid density functional calculations

Abstract

The ferromagnetic (FM)-antiferromagnetic (AFM) transition is experimentally observed in Y1-xLaxTiO3. The underlying microscopic mechanism for FM-AFM transition is still an open problem and far from fully understood. Here, structural, electronic and magnetic properties of Mott insulating Y1-xLaxTiO3 with x = 0, 0.25, 0.5, 0.75, and 1 are studied using hybrid density functional method. Y1-xLaxTiO3 stabilizes in an orthogonal perovskite structure. As x increases, the lattice parameters and unit volume almost increase linearly. Y1-xLaxTiO3 is an FM insulator at x = 0 and 0.25, an A-type AFM insulator at x = 0.5 and 0.75, and a G-type AFM insulator at x = 1. A spin-glass behavior is predicted to emerge at 0.25 < x ≤ 0.5. The calculated lattice parameters, band gaps, and magnetic ground states of Y1-xLaxTiO3 are in good agreement with available experimental data. The Ti–O–Ti bond angels increase with increasing x while the total energy difference between the AFM and FM states decreases and then is less than 0 meV. An FM-AFM phase transition is strongly favored with decrease of the GdFeO3-type distortion. The present study reproduces structural, electronic and magnetic properties of Mott insulating Y1-xLaxTiO3, and interprets well experimentally-observed magnetic phase transition.