Large magnetostriction in Fe-based alloys predicted by density functional theory

Through systematic density functional calculations using the full potential linearized augmented plane-wave method, extraordinary large magnetostrictions are found in Fe-based alloys with appropriate mixing of metalloid and 5d element. For instance, tetragonal magnetostrictive coefficients of Fe87.5Pt6.25Ga6.25 and Fe75Pt6.25Ge18.75 in their model structures can reach to +943 ppm and −3553 ppm, respectively. This was assigned to the availability of nonbonding states around the Fermi level and the large spin-orbit coupling of 5d atoms. The effects of distribution patterns of 5d and metalloid elements and their hybridization are discussed to provide insights for further experimental explorations.