Magnetoresistance in step-edge junctions based on La0.7Sr0.3MnO3 films

The magnetoresistance of step-edge junctions based on La0.7Sr0.3MnO3 films was investigated using a Wheatstone bridge geometry. Two types of step-edge structures were prepared: The step was either fabricated by ion-beam etching of SrTiO3 (001) substrates or by wet-chemical etching of an insulating NdMnO3 layer deposited on SrTiO3 (001). Both the magnetoresistive and insulating layers were deposited by injection-metalorganic chemical vapor deposition. The temperature dependence of the magnetoresistance was explored for both types of junctions in different field orientations. The largest low-field magnetoresistance was obtained when the step was formed directly in the substrate; it was observed up to room temperature (∼1% for an applied field of ∼0.05 T) and at 40 K, it increased ∼12% under an applied field of ∼0.1 T. The hysteretic behavior for the two types of junctions appeared to be very different