Robust magnetism of the cluster assembled (Fe@In6)Ba2 crystal

Abstract

Fe@In6 is the smallest transition metal doped endohedral cage cluster. Its anion, with an octahedral geometry of Oh symmetry, has three singly occupied degenerate orbitals with the ground electronic state 4A1g. Global optimization based on the evolutionary algorithm combined with density functional theories shows that the lowest energy structure of the crystal assembled by Fe@In6 and Ba2 is spin polarized, and the crystal structure is slightly deviated from the fcc (face centered cubic) structure due to the spin-polarization. The magnetic moment is 2.45 μB per Fe@In6Ba2 unit, and the magnetism is very robust. The formation enthalpy of the crystal reaches −1.1 eV per atom, and the spin-polarized state is 2.36 eV lower in energy than the non-polarized state. Calculations also demonstrate that the magnetic moments change linearly with the pressures imposing on the polarization direction. The present study provides a new way for designing cluster assembled magnetic materials by transition metal doped clusters.