Fabrication of MgAl 2 O 4 Thin Films on Ferromagnetic Heusler Alloy Fe 2 CrSi by Reactive Magnetron Sputtering

Epitaxial MgAl 2 O 4 thin films were grown on Heusler alloy Fe 2 CrSi by reactive magnetron sputtering of a MgAl 2 target in an O 2 +Ar atmosphere. To grow MgAl 2 O 4 on Fe 2 CrSi, we inserted a protective layer of MgAl 2 between Fe 2 CrSi and MgAl 2 O 4 to prevent Fe 2 CrSi from being oxidized. Growth of MgAl 2 O 4 was found to be very sensitive to the MgAl 2 thickness and P O2 during deposition of MgAl 2 O 4 . A strong XRD peak of MgAl 2 O 4 (004) was observed with an ultrathin (0.2 nm) MgAl 2 layer. The saturation magnetic moment of Fe 2 CrSi was measured to be 370 emu/cm 3 (1.84 µ B /f.u.) at room temperature and it is expected to have a high spin polarization. The Fe 2 CrSi/MgAl 2 O 4 heterostructure is promising for use in future spintronic devices.