First principles determinations of magnetostriction in transition metals (invited)

The mechanism of magnetostriction in transition metal bulk (fcc Co) and thin films [Co/Pd(001) and Co/Cu(001)] is investigated using the ab initio full potential linearized augmented plane wave method. With the aid of the state tracking and torque approaches the magnetocrystalline anisotropy energy, the essential ingredient of the magnetostriction, is found to be a linear function of the interlayer distances. The calculated magnetostrictive coefficients and magnetoelastic coupling constants for bulk fcc Co agree very well with experiment. The calculated λ001 at the Co/Pd(001) interface is much larger in magnitude (+2.3×10−4) and differs in sign compared to that for Co/Cu(001)(−5.7×10−5). In these thin films, the hybridization between the Co- dxz,yz and the underlying substrate d states is found to play the key role.