Fabrication of Co₂Fe(Al,Si) and Co₂Fe(Al,Si)/MgO on Ge(111) substrate and its magnetic properties

We investigated the interfacial effects on magnetic properties in Co₂Fe(Al,Si)/Ge (CFAS/Ge) and CFAS/MgO/Ge systems to demonstrate the effects of the interface structure on magnetic properties. CFAS and CFAS/MgO were deposited on the i-Ge(111) substrate. In-situ reflection high energy electron diffraction (RHEED) patterns showed epitaxially grown CFAS and MgO on Ge(111). According to the X-ray diffraction (XRD) π-scan of CFAS(220), we determined that the crystallographic orientation relationships were CFAS(111)<-110>// Ge(111)<-110> and CFAS(111)<-110>//MgO(111)<-110>Ge(111)<-110>. The magnetic properties were measured by the vibrating sample magnetometer (VSM) and the saturation magnetization M_s value of CFAS with 2-nm thick MgO reached the value of L2₁ ordered one. A uniaxial magnetic anisotropy behavior was observed both in CFAS/Ge and CFAS/MgO/Ge structures after annealing. We confirmed the behavior did not only originate from the CFAS/Ge interface but also CFAS/MgO and the ordering structure.