Non-equilibrium magnetic fields in ab initio spin dynamics

Abstract

Starting from the continuity equation for the magnetization in time-dependent spin-density functional theory, we derive an expression for the effective time-dependent magnetic fields driving the out-of-equilibrium spin dynamics in magnetic systems. We evaluate these, so called, kinetic magnetic fields in the ultrafast demagnetization response to optical pulse excitations of ferromagnetic iron-based materials, namely Fe${}_6$ cluster and bulk bcc Fe. We identify spatial "hot spots" where the demagnetization is particularly enhanced as a result of the increased kinetic torque.

8 pages, 5 figures version 02 theory section and appendix modified, results unchanged

References in corpus (4)

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• Dynamics of spin 1/2 quantum plasmas
• Comparison of exact-exchange calculations for solids in current-spin-density- and spin-density-functional theory
• The role of spin-orbit interaction in the ultrafast demagnetization of small iron clusters

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