Structural, 1/f Noise and MOKE Characterization of Vicinal La0.7Sr0.3MnO3 Thin Films

This paper presents some structural, magnetic and electrical properties of 40 nm and 75 nm thick La0.7Sr0.3MnO3 thin films deposited on vicinal SrTiO3(001) substrates. The vicinal angles were 2, 4, 6, 8, and 10º from the [001] direction towards [110]. Standard SrTiO3(001) substrates were used for comparison and for the growth condition optimization. Structural properties were studied by X-ray diffraction, which indicated that the LSMO films grew with their (001) axis coincident with the (001) axis of the substrate. The surface morphology was carefully studied by atomic force microscopy in tapping mode. Very smooth films and regular step-terrace structures on the La0.7Sr0.3MnO3 surfaces could be observed. The root mean square roughness measured in 2μ m×2μ m images was in the 0.130-0.580 nm range for all angles and both thicknesses. Superconducting quantum interference device magnetometer measurements revealed a Curie temperature in the 340-350 K range and magneto-optical Kerr microscopy enabled magnetic domain imaging and hysteresis loop measurements at 300 K. A uniaxial easy magnetization direction was obtained at 300 K for angles above 4º, with the easy axis along the steps. Finally, preliminary 1/f noise measurements were performed at 300 K for bias currents along and perpendicular to the step direction, showing a noise level as low as that we typically measured on standard SrTiO3(001) substrates. All these results are promising for the future realization of room-temperature devices making use of the anisotropy of the magnetization.