The Effect of A-Site Substitution of Ce and La on the Magnetic and Electronic Properties of Sr(Ti0.6Fe0.4)O3-δ Films

The structure and magnetic properties of epitaxial (CexSr1-x)(Ti0.6Fe0.4)O3-delta (x = 0, 0.1, 0.2 and 0.3) and (LaxSr1-x)(Ti0.6Fe0.4)O3-delta (x = 0, 0.1, 0.2, 0.3 and 0.4) perovskite-structure thin films deposited by pulsed laser deposition on (LaAlO3)(0.3)(Sr2AlTaO6)(0.7) (LSAT) substrates are reported. Both La and Ce ions showed a dominant 3+ valence state and acted as donors on the Sr2+ site (A site) in the perovskite lattice. The optical band gap widened, and the Fermi level moved toward the vacuum level with increased Ce or La content; meanwhile the Ti and particularly the Fe ions were driven to a lower valence state, resulting in a higher Fe2+ concentration. The materials were magnetic at room temperature with up to 0.8 mu(B)/Fe and a magnetoelastic out-of-plane anisotropy. Ce and La lowered the coercivity while raising both the Faraday rotation at 1550 nm and the optical absorption at near-infrared wavelengths.