A multiscale model of the efect of Ir thickness on the static and dynamic properties of Fe/Ir/Fe flms

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.
Gino Hrkac (GH) acknowledges support from the Vienna Science and Technology Fund (WWTF) under Grant No. MA14-44, through the EPSRC Grant No. EP/K008412/1, and from the Royal Society under Grant No. UF080837. Thomas A Ostler (TAO) gratefully acknowledges the support of the Marie Curie incoming BeIPD-COFUND fellowship program at the University of Liège. Ramon Cuadrado (RC) acknowledges the funding from the European Union’s Horizon 2020 research and innovation programme under the Marie Sklodoswa-Curie grant agreement No. 665919. ICN2 is supported by the Severo Ochoa program from Spanish MINECO (Grant No. SEV-2013-0295). László Oroszlány (LO) and László Szunyogh (LS) are grateful for the support by the Hungarian National Scientific Research Fund (NKFIH) under project Nos. K115575, K108676, K115608 and FK124723. L. O. also acknowledges support from the Janos Bolyai Scholarship of the Hungarian Academy of Sciences as well as the National Quantum Technologies Program 2017-1.2.1-NKP-2017-00001 of the NRDI Office of Hungary. This project has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement No 737093, FEMTOTERABYTE as well as the financial support of the Advanced Storage Technology Consortium and Seagate Technology.