Magnetic interactions in Cr2Ge2Te6 and Cr2Si2Te6 monolayers: ab initio study

Abstract

Magnetic anisotropy in low dimensional semiconductors can lead to long-range ferromagnetic order. This feature is useful for various applications such as spintronic and sensoric. The exchange interaction integrals have been observed through magnetic, structural and electronic properties of Cr2Ge2Te6 and Cr2Si2Te6 first-principles simulation in the VASP software package and Heisenberg model approach. The structural parameters for the bulk layered Cr2Ge2Te6 and Cr2Si2Te6 were determined and in good agreement with the experiment. Calculations have established that the number of layers does not affect the magnetic properties and entire magnetic moment is localized on Cr atoms. Exchange interaction integrals between the first, second and third neighbors have been calculated for monolayers. The dependence of the exchange interaction integral on the Hubbard coefficient has been established. The exchange integral with the first neighbors J1 was -2.34 (Cr2Ge2Te6) and -1.61 (Cr2Si2Te6) meV at the Hubbard coefficient of 3 eV. Thus, strong ferromagnetic order exists in plane of monolayers of Cr2Ge2Te6 , Cr2Si2Te6 and magnetic anisotropy leads to long-range ferromagnetism.