Magnetism and ultra-fast magnetization dynamics of Co and CoMn alloys at finite temperature

Abstract

Temperature-dependent magnetic experiments like pump-probe measurements generated by a pulsed laser have become a crucial technique for switching the magnetization in the picosecond time scale. Apart from having practical implications on the magnetic storage technology, the research field of ultrafast magnetization poses also fundamental physical questions. To correctly describe the time evolution of the atomic magnetic moments under the influence of a temperature-dependent laser pulse, it remains crucial to know if the magnetic material under investigation has magnetic excitation spectrum that is more or less dependent on the magnetic configuration, e.g. as reflected by the temperature dependence of the exchange interactions. In this article, we demonstrate from first-principles theory that the magnetic excitation spectra in Co with fcc, bcc and hcp structures are nearly identical in a wide range of non-collinear magnetic configurations. This is a curious result of a balance between the size of the magnetic moments and the strength of the Heisenberg exchange interactions, that in themselves vary with configuration, but put together in an effective spin Hamiltonian results in a configuration independent effective model. We have used such a Hamiltonian, together with ab-initio calculated damping parameters, to investigate the magnon dispersion relationship as well as the ultrafast magnetisation dynamics of Co and Co-rich CoMn alloys.

References in corpus (6)

• Identification of the dominant precession damping mechanism in Fe, Co, and Ni by first-principles calculations
• Quantitative simulation of temperature dependent magnetization dynamics and equilibrium properties of elemental ferromagnets
• Microscopic origin of Heisenberg and non-Heisenberg exchange interactions in ferromagnetic bcc Fe
• First-principles prediction of high Curie temperature for ferromagnetic bcc-Co and bcc-FeCo alloys and its relevance to tunneling magnetoresistance
• All-thermal switching of amorphous Gd-Fe alloys: analysis of structural properties and magnetization dynamics
• Electronic topological transition and non-collinear magnetism in compressed hcp Co

Cited by in corpus (8)

• Non-local Gilbert damping tensor within the torque-torque correlation model
• First-principles Dzyaloshinskii-Moriya interaction in a non-collinear framework
• Analysis of the linear relationship between asymmetry and magnetic moment at the M-edge of 3d transition metals
• Mechanisms behind large Gilbert damping anisotropies
• Comparative study of methodologies to compute the intrinsic Gilbert damping: interrelations, validity and physical consequences
• Influence of non-local damping on magnon properties of ferromagnets
• Spin-lattice couplings in $3d$ ferromagnets: analysis from first-principles
• Tracing magnetic atom diffusion with annealing at the interface between CoMn alloy and MnGa layer by X-ray magnetic circular dichroism