Magnetic states of Mn and Co atoms at Co2MnGe/MgO interfaces seen via soft x-ray magnetic circular dichroism

摘要: The magnetic states of Mn and Co atoms in Co-rich ${\text{Co}}_{2}\text{MnGe}$ Heusler alloy thin films facing an MgO barrier were studied by means soft x-ray circular dichroism (XMCD). In particular, the film-thickness dependence moments was investigated. With a decrease film thickness to 1--2 monolayers (MLs), spin moment decreased $\text{Mn}\text{ }{L}_{2,3}$-edge absorption spectra (XAS) showed ${\text{Mn}}^{2+}$-like multiplet structure MnO, contrast samples thicker than 4 ML, indicating that 1 2 ML oxidized. increased slightly with decreasing thickness. A ${\text{Co}}^{2+}$-like CoO not observed all $\text{Co}\text{ XAS XMCD, that, even ultrathin samples, oxidized, more strongly polarized those samples. $1.40--1.77\text{ }{\ensuremath{\mu}}_{\text{B}}$ larger theoretical value for ideal stoichiometric $(\ensuremath{\sim}1\text{ }{\ensuremath{\mu}}_{\text{B}})$ composition imply presence antisites would lower polarization.