Control of magnetic anisotropy in epitaxial Co2MnAl thin films through piezo-voltage-induced strain

Abstract

The voltage-controlled magnetic anisotropy of various magnetic materials is an effective method to realize the electronic devices with low power consumption. Here, we investigated the magnetic properties in Co2MnAl/GaAs heterostructures controlled by piezo voltages-induced strain using the magneto-optical Kerr effect microscopy. The coexistence of the in-plane cubic and uniaxial magnetic anisotropies was observed in the initial state of Co2MnAl thin films. The magnetic anisotropy was manipulated effectively by the piezo voltages. The two-step magnetic hysteresis loop measured along the [1−10] direction was changed into a square loop when the piezo voltage was −30 V (compressed state). On the contrary, the loop of the [110] direction was changed into a two-step loop. The loops of [100] and [010] axes represented the hard axes and were almost unchanged with the piezo voltages. We found that the transformations of loops in [110] and [1−10] axes were manipulated by the piezo voltage induced additional uniaxial anisotropy. Finally, we demonstrated that the planar Hall resistance (RH) in the Hall device can be effectively controlled by the piezo voltages. Our study identified that the voltage controlled room temperature magnetic devices through strain engineering could have great potential for spintronic applications.