Temperature dependence of the higher order magnetic anisotropies in Co/Au layered structures

Second- and fourth- order K 2 , K 4 constants of the magnetic anisotropy of ultrathin (0.8-1.5 nm) Co layers in [Py/Au/Co/Au] 15 multilayer structures have been determined as a function of temperature from 100 to 600 K. We found that K 2 of order of 1 MJ/m 3 monotonically decreases with temperature while K 4 of the order of 10 -2 x K 2 is temperature independent. We also estimated the temperature dependence of the volume K 2 V and surface K 2 S terms of K 2 . K 2 V varies almost linearly with temperature and is at room temperature noticebly larger than the magnetocrystalline anisotropy of bulk Co. K 2 S is temperature independent. The results are qualitatively compared with anisotropy data of bulk Co.