2009 Volume 34 Issue 1 Pages 43-46
Epitaxial thin films of Bi1-xBaxFeO3 have been deposited by sputtering on LaAlO3 and SrTiO3 substrates with and without conducting buffer layers of paramagnetic LaNiO3 and ferromagnetic La0.7Sr0.3MnO3, and their structural, magnetic and ferroelectric properties have been investigated. It has been shown from magnetic and ferroelectric characterization that Bi1-xBaxFeO3 epitaxial films in a thickness of 300 nm exhibited reasonable multiferroic properties at room temperature. Spin-filter junctions consisting of a La0.7Sr0.3MnO3/ Bi1-xBaxFeO3/LaNiO3 epitaxial heterostructure have been fabricated using photolithography and ion milling. The junctions with a Bi1-xBaxFeO3 layer thickness of 4 nm exhibited nonlinear current-voltage (I-V) characteristics with the barrier height of 0.37 eV, and MR effect at 4.2 K, indicating that the Bi1-xBaxFeO3 ultrathin layers serves as ferromagnetic tunnel barriers in spin-filter junctions.