Epitaxial LSMO films grown on MgO single crystalline substrates

The manganite La_0.67Sr_0.33MnO₃ (LSMO) layers are deposited on single crystal MgO(0 0 1) substrates using a magnetron dc sputtering. The crystalline perfection of the layers, both the as-prepared and the annealed, are characterized by X-ray diffraction technique, rocking curve measurements, Rutherford backscattering spectroscopy (RBS) and transmission electron microscopy (TEM). TEM analyses give evidence of the epitaxial growth of the annealed LSMO with a nanocrystalline surface layer. The temperature dependence of resistance in the 77-340 K range is measured by a standard four-probe technique. While the as-prepared film does not show any transition from paramagnetic to ferromagnetic state, the film annealed in oxygen shows steep R(T) dependence with a peak at 330 K and maximal slope (dR/dT) at 290 K where the maximal sensitivity is 3% K⁻¹.