Antiferromagnetic energy loss and exchange coupling of IrMn/CoFe films: experiments and simulations

Abstract

The energy loss density E 2 π and the coupling energy density J of antiferromagnetic (1 1 1) textured IrMn films of different thickness t sputtered onto ferromagnetic CoFe films have been measured by torque magnetometry for high in-plane rotating magnetic fields at a low temperature ( T=10 K). The results are compared with model calculations which assume independent grains of equal size with a statistical distribution of individual grain coupling energies. Analytical expressions for E 2 π ( t) and J( t) are used to explain the measurements for small thicknesses t<3.5 nm. The simulations fit the experiments well if a thickness dependent triaxial anisotropy energy constant K( t) is introduced. At t=3 nm, K≈1.3×10 5 J/m 3.