Growth and magnetic properties of multiferroic Lax Bi1-x Mn O3 thin films

Abstract

A comparative study of Lax Bi1-x Mn O3 thin films grown on SrTi O3 substrates is reported. It is shown that these films grow epitaxially in a narrow pressure-temperature range. A detailed structural and compositional characterization of the films is performed within the growth window. The structure and the magnetization of this system are investigated. We find a clear correlation between the magnetization and the unit-cell volume that we ascribe to Bi deficiency and the resultant introduction of a mixed valence on the Mn ions. On these grounds, we show that the reduced magnetization of Lax Bi1-x Mn O3 thin films compared to the bulk can be explained quantitatively by a simple model, taking into account the deviation from nominal composition and the Goodenough-Kanamori-Anderson rules of magnetic interactions. © 2007 The American Physical Society.