Effects of GaAs buffer layer on quantum anomalous Hall insulator V<i>y</i>(Bi<i>x</i>Sb1−<i>x</i>)2−<i>y</i>Te3

We report the growth, structural characterization, and transport properties of the quantum anomalous Hall insulator Vy(BixSb1−x)2−yTe3 (VBST) grown on a GaAs buffer layer by molecular beam epitaxy on a GaAs(111)A substrate. X-ray diffraction and transmission electron microscopy show that the implementation of a GaAs buffer layer improves the crystal and interface quality compared to the control sample grown directly on an InP substrate. Both samples exhibit the quantum anomalous Hall effect (QAHE), but, with similar thermal stability despite their different structural properties. Notably, the QAHE in the sample grown on a GaAs buffer layer displays a significantly larger (almost double) coercive field with a much smaller resistivity peak at magnetization reversal. Possible effects of the interface quality on the magnetic properties of VBST and the QAHE are discussed.