Testing spin-flip scattering as a possible mechanism of ultrafast demagnetization in ordered magnetic alloys

Abstract

International audienceWe use element-resolved IR-pump/extreme ultraviolet-probe experiments to disentangle the ultrafast interplay of the magnetic sublattices of an ordered crystalline magnetic alloy. As a paradigmatic example, we investigate the case of the FeRh alloy, which shows a delayed response for the different components. Furthermore, a detailed time-resolved magneto-optic study shows that the data can be analyzed by only assuming Elliot-Yafet-like scattering, as the underlying mechanism for ultrafast demagnetization, resulting in an unexpected nonmonotonic dependence of the spin-flip rate, as a function of quenching

Multiscale modeling of ultrafast element-specific magnetization dynamics of ferromagnetic alloys

“…From a fundamental viewpoint, however, it is also important to understand the element-specific magnetization dynamics in multielement ferromagnetic alloys. This is challenging from a modeling perspective and, moreover, contradicting results have been observed in NiFe alloys [24][25][26].…”

“…Using extreme ultraviolet pulses from high-harmonic generation sources Mathias et al [24] probed element specifically the ultrafast demagnetization in Py and obtained the same demagnetization rates for each element, Fe and Ni, but with a 10 to 70 fs delay between them. These dynamics were successfully reproduced by Günther et al [25] using the timeresolved magneto-optic Kerr effect in the extreme ultraviolet domain in combination with an infrared pump laser. However, recently Radu et al [26] measured Py in the soft-x-ray regime and obtained different demagnetization rates, with Ni being significantly faster than Fe.…”

All-optical switching in ferromagnetic superlattices.

“…The heat accumulation temperature for this absorbed power gives a Curie temperature T C = 610 K, consistent with results in similar samples of T C = 800 K for Co/Pd and T C = 600 K for Co/Pt [65]. scattering is proportional to the magnetization variation dM(τ)/dτ [63][64][65]92]. Indirect electron-induced UDM from the glass plasma [107] may also contribute, as also seen in Co/Pd multilayers capped with Al [80].…”

“…materials[33][34][35][46][47][48]. T e and T s have strong variations over a few ps, after which all three temperatures are the same T=T p =T s =T e , gradually decreasing toward the initial temperature.…”

Structural dynamics during laser-induced ultrafast demagnetization

“…One of the most broadly accepted models is based on Elliott-Yafet like splin-flip scattering. 5,40 More recently, it was proposed that the rapid magnetization quenching were due to superdiffusive spin transport out of the excited/probed sample area by the excited spin polarized valence electrons. 6 Several experiments gave evidence for the presence of this mechanism.…”