Manganite Heterostructures SrIrO₃/La_0.7Sr_0.3MnO₃ and Pt/La_0.7Sr_0.3MnO₃ for Generation and Registration of Spin Current

This paper presents the results of experimental studies of the cross section of the interfaces of the SrIrO₃/La_0.7Sr_0.3MnO₃ and Pt/La_0.7Sr_0.3MnO₃, heterostructures, in which, upon excitation of ferromagnetic resonance in a La_0.7Sr_0.3MnO₃ film, a spin current arises that flows through the interface in structure. Epitaxial growth of thin films of strontium iridate SrIrO₃ and manganite La_0.7Sr_0.3MnO₃ on a (110)NdGaO₃ single-crystal substrate was carried out using magnetron sputtering at a high temperature in a mixture of argon and oxygen gases. The spin mixing conductance, which determines the amplitude of the spin current and generally has real Re g^↑↓ and imaginary Im g^↑↓ parts, was determined from the frequency dependence of the FMR spectrum of the La_0.7Sr_0.3MnO₃ film and the heterostructures. It is shown that the Im g^↑↓ quantity can play an important role in determining the spin Hall angle (θ_SH) from the angular dependence of the spin magnetoresistance. For the SrIrO₃/La_0.7Sr_0.3MnO₃ heterostructures, θ_SH turns out to be significantly higher (almost an order of magnitude) than that for the Pt/La_0.7Sr_0.3MnO₃ heterostructure.