Multi-layer Interface by X-Ray Magnetic Circular Dichroism (XMCD) Measurement*

Interface effect of heterostructure due to spin, orbital and charge interaction provide abundant exotic phenomena. In this study, the magnetic properties of Cu and Mn at the interfaces of YBa₂Cu₃O₇/La_0.7Sr_0.3MnO₃ multi-layer system is carried out by an X-Ray Magnetic Circular Dichroism (XMCD) measurement on the L-edges at various magnetic field intensities and temperatures. The magnetic polarizations of both Cu and Mn are parallel to the external field. Results show that the total magnetic moments decrease with increasing magnetic field intensity. The orbital moments of Cu at interfaces are not quenched and have larger values than that of the spin moments. For Cu at 0.1 T, m_orb/m_spin is ~2.3 with a total moment of ~1μ_B. This result indicates that there is a possible spin-split coupling for LSMO layer that affects a thin layer of one or two unit cells near the interface of YBCO, altering the environment of Cu ions which leads to an asymmetric distribution of crystal field. Moreover, it is observed that there is a sufficient amount of decrease in the Cu orbital moment from 0.3 T to 0.4 T, while the spin magnetic moment shows a continuously exponential decay.