Controlling the electrical and magnetic ground states by doping in the complete phase diagram of titanate Eu1-xLaxTiO3 thin films

TL;DR

This study synthesizes Eu1-xLaxTiO3 thin films across the full doping range, revealing a complex phase diagram with tunable electrical and magnetic ground states driven by La doping, advancing understanding of strongly-correlated oxides.

Contribution

It provides the complete phase diagram of Eu1-xLaxTiO3, demonstrating how doping controls the transition from insulating to metallic and magnetic states in titanate thin films.

Findings

Eu1-xLaxTiO3 films show electron conduction with varying carrier densities.

Magnetic states evolve from antiferromagnetic insulator to various metallic and magnetic phases.

The phase diagram is mapped out across the full doping range.

Abstract

EuTiO3, a band insulator, and LaTiO3, a Mott insulator, are both antiferromagnetic with transition temperatures ~ 5.5 K and ~ 160 K, respectively. Here, we report the synthesis of Eu1-xLaxTiO3 thin films with x = 0 to 1 by oxide molecular beam epitaxy. The films in the full range have high crystalline quality and show no phase segregation, allowing us carry out transport measurements to study their electrical and magnetic properties. From x = 0.03 to 0.95, Eu1-xLaxTiO3 films show conduction by electrons as charge carriers, with differences in carrier densities and mobilities, contrary to the insulating nature of pure EuTiO3 and LaTiO3. Following a rich phase diagram, the magnetic ground states of the films vary with increasing La-doping level, changing Eu1-xLaxTiO3 from an antiferromagnetic insulator to an antiferromagnetic metal, a ferromagnetic metal, a paramagnetic metal, and back to an antiferromagnetic insulator. These emergent properties reflect the evolutions of the band structure, mainly at the Ti t2g bands near the Fermi level, when Eu2+ are gradually replaced by La3+. This work sheds light on this method for designing the electrical and magnetic properties in strongly-correlated oxides and completes the phase diagram of the titanate Eu1-xLaxTiO3.