Tuning Magnetic Anisotropy Of Manganite Oxide By Interface Coupling

Due to the strong coupling between spin,charge,lattice and orbital degree of freedom,perovskite manganite exhibit abundant exotic properties.In recent years,many works focused on the impact of interfaces in heterostructures,especially perovskite/perovskite heterostructures.So far,numerous properties have been found in perovskite/perovskite heterostructures,such as magnetic anisotropy,2-dimentional electron gas.In this paper,we designed perovskite/brownmillerite heterostructures and investigated the impact on magnetism of interface coupling and strain.The results are as follows:1.We prepared LaCoO₃/La_0.67Sr_0.33MnO₃/LaCoO₃ tri-layers on?110?-oriented SrTiO₃ substrate and investigated the crystal structure.The films are of high crystal quality.We can found the dark stripes which are at an angle of 45 degrees to the inerface,in other words,the dark stripes are along the[100]or[010]axis.Not only the La-La distance across the dark stripes in LaCoO₃,but also in La_0.67Sr_0.33MnO₃near the interface is larger than elsewhere,which result in distortion of crystal lattices.The MnO₆ octahedra at interface is stretched along[100]or[010]axis.2.We tuned the magnetic orientation of La_0.67Sr_0.33MnO₃,the single layer's easy axis is[001]in plane,while the tri-layers'easy axis is[1-10]in plane.The anisotropy constant is 10⁶erg/cm³ and two orders of magnitude greater than single layer.Anisotropy constant exhibits a well linear dependence on the reciprocal of La_0.67Sr_0.33MnO₃ layer's thickness,which means the interface coupling result in orbital reconstruction thus the change of magnetic orientation.Replace La_0.67Sr_0.33MnO₃ with La_0.67Ba_0.33MnO₃,we can tune the magnetic orientation of La_0.67Ba_0.33MnO₃ tri-layers in KTO substrate,which confirm the influence of strain.