Electrical Properties of Epitaxial Thin Films of OxyhydridesATiO3–xHx(A = Ba and Sr).

Wehave studied electronic properties of perovskite oxyhydridesATiO3–xHx(A = Ba, Sr). Epitaxial thin films of ATiO3–xHxwith various hydridecompositions, up to x= 0.58 for Ba and x= 0.45 for Sr, are prepared by the low-temperature CaH2reduction of the corresponding oxide films deposited on (LaAlO3)0.3(SrAl0.5Ta0.5O3)0.7(LSAT) substrates by pulsed laser deposition. Resistivitymeasurements for A = Sr show a metallic phase over a wide range ofH–composition, implying a substantial stabilizationof H 1s orbitals that should be distributed over O 2p orbitals. Onthe other hand, for A = Ba, a semiconducting behavior is seen up to∼5–8% of H–substitution. Interestingly,a similar contrasting behavior is observed in a Nb-substituted BaTiO3and SrTiO3, which suggests that a local cation–offcentering in lightly doped Ba films creates in-gap states in the bandstructure (as opposed to the Sr films), hindering the electron transport. [ABSTRACT FROM AUTHOR]