Modified magnetism in heterostructures of Cr2Ge2Te6 and oxides

Abstract

We study the effects of interfacing the van der Waals ferromagnet Cr2Ge2Te6 with oxide layers, such as NiO and MgO, in a few different configurations. For this, the magnetic hysteresis curves, obtained by magneto optical Kerr effect, of Cr2Ge2Te6 flakes of similar thicknesses were evaluated. Compared to the properties of a bare Cr2Ge2Te6, we observed an increased perpendicular magnetic anisotropy and enhanced Curie temperature in the Cr2Ge2Te6/NiO heterostructure. In contrast, we report little or no change of the magnetic properties in a Cr2Ge2Te6/NiO and Cr2Ge2Te6/MgO where the Cr2Ge2Te6 was exfoliated on top of the oxide layer. Finally, strain is considered as the mechanism of the enhancement, as we observed the formation of wrinkles in thin Cr2Ge2Te6/NiO heterostructure and the Raman characteristics close to the wrinkles indicated a tensile strain, which is consistent with stronger ferromagnetism in Cr2Ge2Te6.