A multiscale model of the effect of Ir thickness on the static and dynamic properties of Fe/Ir/Fe films

Abstract

The complex magnetic properties of Fe/Ir/Fe sandwiches are studied using a hierarchical multi-scale model. The approach uses first principles calculations and thermodynamic models to reveal the equilibrium spinwave, magnetization and dynamic demagnetisation properties. Finite temperature calculations show a complex spinwave dispersion and an initially counter-intuitive, increasing exchange stiffness with temperature (a key quantity for device applications) due to the effects of frustration at the interface, which then decreases due to magnon softening. Finally, the demagnetisation process in these structures is shown to be much slower at the interface as compared with the bulk, a key insight to interpret ultrafast laser-induced demagnetization processes in layered or interface materials.

Simulations of magnetization reversal in FM/AFM bilayers with THz frequency pulses

“…In the simulations, the exchange coupling at the interface is varied from J ( of the n.n used for Py) to J. The interface coupling is chosen as a variable quantity in our simulations as it can be manipulated experimentally by the insertion of a non-magnetic spacer between the FM and AFM 37 or doping at the FM/AFM interface. For the simulations of Mn Au and Permalloy bilayers, there are two additional Hamiltonian terms: The first term in the above can be found in Eq.…”