Ferromagnetism and exchange bias in a diluted magnetic ferroelectric oxide

Abstract

We report on the observations of room-temperature ferromagnetism and ferroelectricity in the epitaxial thin film of ${\text{BaTi}}_{0.98}{\text{Co}}_{0.02}{\text{O}}_{3}$ (CBTO) with detailed structural and magnetic analyses. The films are single phase with an inhomogeneous distribution of ${\text{Co}}^{2+}$ dopants in the structure. Room-temperature ferromagnetic hysteresis and ferroelectric loop were observed. Remarkably, the hysteresis loops for field cooling show the exchange bias and training effects. The complex magnetic behavior of CBTO was interpreted in the frame of bound magnetic polaron formation with inhomogeneity of dopant distribution. This work also demonstrated that exchange bias can be a helpful technique in exploring the mechanism of dopant-induced ferromagnetism.