Magnetic Coupling in La0.67 Ca0.33 MnO3／La0.67 Sr0.33 CoO3／La0.67 Ca0.33MnO3 Trilayer Films
摘要
The perovskite La0.67Ca0.33MnO3/La0.67Sr0.33CoO3/La0.67Ca0.33MnO3 trilayers were fabricated by a facing-target sputtering technique and their magnetotransport properties were investigated. The magnetoresistance is dependent on spacer thickness and dramatically decreases when La0.67Sr0.33CoO3 layer is thick enough because of its short-circuiting effect. Different from La0.67Ca0.33MnO3 single layer, trilayer films with thin La0.67Sr0.33CoO3 spacer have the enhanced metal-semiconductor transition temperature (TMS) of La0.67Ca0.33MnO3 layers. The magnetic coercivity HC shows a nonmonotonic behavior with changing the spacer layer thickness at 230 K. The waist-like hysteresis indicates that there is an indirect exchange coupling between the top and bottom La0.67Ca0.33MnO3 layers across the spacer La0.67Sr0.33CoO3 layer.