Mn–O and Mn–Mn interatomic distances were determined in LaxCa1−xMnO3 films grown heteroepitaxially on single crystal SrTiO3 and LaAlO3 substrates by molecular beam epitaxy. Mn–O bond lengths were found to be fixed at ∼1.975 Å for both types of substrates, while the Mn–Mn distance was detected to be larger for films grown on SrTiO3 substrates than for films grown on LaAlO3. The deviation of Mn–Mn interatomic distances, and subsequently Mn–O–Mn bond angles, in epitaxial LaxCa1−xMnO3 films is attributed to the misfit strain: compressive for LaAlO3 and tensile for SrTiO3 substrates.

In this letter we show that GdOyHx thin films allow one to tailor the electric and the optical properties by controlling the hydrogen and oxygen content. By changing the O/H ratio, one can shift the optical band gap from 2.4 eV in the trihydride to 5.4 eV in the pure oxide. The GdOxHy (x<1.5, y<2) thin films are insulating, and a resistivity as high as 1010 Ω cm, as compared to 10−4 Ω cm in the metallic state, is obtained. The thermal stability of the films depends strongly on the oxygen concentration. Samples with low oxygen content can be switched between the insulating and conducting state by reducing the hydrogen content. A reversible resistivity change of 106 Ω cm is demonstrated.

We determined the changes of the local structure of the V layers in a single-crystal Fe͑3 ML͒/V͑13 ML͒ ͑001͒ superlattice upon loading with hydrogen using Extended X-ray Absorption Fine Structure ͑EXAFS͒. Going from V to VH 0.5 , the initial bct structure is strongly distorted and resembles the local structure of bulk ␤-V hydride. The obtained out-of-plane lattice parameter is a sequence of 3.18 Åϩ(Ϫ1) i 0.41 Å, i ϭ0,1,2, . . . , yielding a lattice expansion of 7.3%. The resulting average expansion of the entire V layeraccounting for the hydrogen-depleted interface regions-amounts to 5.1%, and is consistent with previous results from XRD.

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Large negative magnetoresistance and magnetisation anomalies are found in epitaxial GdH3 − δ films. The zero-field semiconductor-like behavior in the resistivity is completely suppressed at a magnetic field of 120 kOe. Temperature and field dependence of the magnetisation supports short-range ordering in the paramagnetic host, mediated by the vacancy state of trihydride.