FIRST PRINCIPLES DETERMINATIONS OF MAGNETOSTRICTION IN TRANSITION-METALS

The mechanism of magnetostriction in transition metal bulk (fee Co) an d 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 magnetocrystallin e anisotropy energy, the essential ingredient of the magnetostriction, is found to be a linear function of the interlayer distances. The cal culated magnetostrictive coefficients and magnetoelastic coupling cons tants for bulk fee Co agree very well with experiment. The calculated lambda(001) at the Co/Pd(001) interface is much larger in magnitude (2.3x10(-4)) and differs in sign compared to that for Co/Cu(001)(-5.7x1 0(-5)). In these thin films, the hybridization between the Co- d(xz,yz ) and the underlying substrate d states is found to play the key role. (C) 1996 American Institute of Physics.