Non-Synchronized Rotation of Layered Spin Configurations in La 0.825Sr 0.175MnO 3/SrTiO 3 Film

Magnetic properties of single perovskite-structure epitaxial film are reported to have layered distribution recently. However, the different responses of spin configurations in individual layers to the variation of temperature and strain state, especially the subtle response of layered film due to structural phase transformation of SrTiO₃ (STO) substrate around 105 K, have not been revealed completely. Drastic drop and concomitant abnormal increase of remnant magnetic moments (REM) and coercivity of low-doped La_1-xSr_xMnO₃ (x=0.175) /SrTiO₃ film were observed for the first time around 105 K only in the in-plane direction, and layered magnetic structures were further inferred based on investigation of microstructure, strain distribution and chemical inhomogeneity. Abnormal change of magnetic properties around 105 K was discussed by a three-layer model, in which softer ferromagnetic layer was supposed to form in the middle layer of strain induced layered structure, and the spin configuration of middle layer underwent non-synchronous transformation relative to other parts of the film, which may be attributed to the change of in-plane strain inside the film around 105 K. Our work reveals the variation of individual magnetic layers with the increase of temperature through utilizing the remnant magnetic field in measuring system, and the abrupt reversal of spin configuration at the intermediate layer can also serve the design of novel spintronics devices in the future.