Magnetocrystalline anisotropy in FePt with L1 ordering and tetragonal distortion

We evaluate the magnetocrystalline anisotropy energy of L10 type FePt alloys with the lattice distortion and atomic disorder by using the first-principles calculation, which adopts the tight-binding linear muffin-tin orbital method in conjunction with the coherent potential approximation techniques. The calculated result indicates that the magnetocrystalline anisotropy energy is quite sensitive to the mentioned factors. In particular, it is drastically decreased with the degree of ordering compared with the expected value from the completely ordered structure. We will suggest that the improvement of the chemical ordering of the L10 crystal is one of the significant points to obtain a large magnetocrystalline anisotropy from FePt compounds.