  Voltage control of magnetic anisotropy (VCMA) in magnetic heterostructures is
a key technology for achieving energy-efficiency electronic devices with
ultralow power consumption. Here, we report the first demonstration of the VCMA
effect in novel epitaxial Ru/Co2FeAl(CFA)/MgO heterostructures with interfacial
perpendicular magnetic anisotropy (PMA). Perpendicularly magnetized tunnel
junctions with the structure of Ru/CFA/MgO were fabricated and exhibited an
effective voltage control on switching fields for the CFA free layer. A large
VCMA coefficient of 108 (139) fJ/Vm for the CFA film was achieved at room
temperature (4 K). The interfacial stability in the heterostructure was
confirmed by repeating measurements. Temperature dependences of both the
interfacial PMA and the VCMA effect were also investigated. It is found that
the temperature dependences follow power laws of the saturation magnetization
with an exponent of ~2. The significant VCMA effect observed in this work
indicates that the Ru/CFA/MgO heterostructure could be one of the promising
candidates for spintronic devices with voltage control.
