Subpicosecond Magnetization Reversal across Ferrimagnetic Compensation Points

Abstract

Subpicosecond magnetization reversal is experimentally demonstrated by ultrafast heating of a ferrimagnet across its compensation points, under an applied magnetic field. While the reversal is initiated by crossing the magnetization compensation temperature, the short reversal time is related to the angular momentum compensation, where the dynamics of the system is highly accelerated owing to the divergence of the gyromagnetic ratio. These results demonstrate the feasibility of subpicosecond magnetization reversal previously believed impossible.

Crystallographically amorphous ferrimagnetic alloys: Comparing a localized atomistic spin model with experiments

“…The fastest precessional reversal demonstrated experimentally using an external magnetic field 2,3 is ∼100 ps, with similar reversal times achieved using a spin-polarized current. [4][5][6] Recent experimental work in the field of magneto-optics has demonstrated that carefully shaped laser pulses can be used to manipulate the magnetization dynamics on the subpicosecond time scale [7][8][9][10][11][12] in many materials, including cobalt, iron, nickel, and GdFeCo. However, controllable magnetization switching has only been observed in GdFeCo, and this has stimulated a great deal of effort to attempt on many levels to explain the process.…”

“…The excitement for these materials has recovered in the past few years with the observation of ultrafast magnetization switching using femtosecond laser pulses. 10 The atomistic model is currently the only model that can describe ultrafast magnetic processes associated with these types of ferrimagnets, however, to the best of our knowledge, the atomistic model has not yet been applied to such disordered ferrimagnets.…”

Role of electron and phonon temperatures in the helicity-independent all-optical switching of GdFeCo

“…In addition, we performed experiments on sample Gd 24 FeCo (black down triangles in Fig.2 at T > T M where no transition through T M was possible due to laser heating. This means that field induced switching scenarios due to crossing of T M can be discarded 34 . Fig.3 shows the fluence dependence of the magnetization evolution in Gd 24 FeCo at T = 300 K and for ∆t = 55 fs.…”

Ultrafast heating as a sufficient stimulus for magnetization reversal in a ferrimagnet

“…In recent years, owing to an increased interest in ferrimagnetic materials, there have been a number of studies of ultrafast magnetic switching based on increasing the temperature of a ferrimagnetic material over its magnetic compensation point with the help of a short laser pulse [6][7][8] . These studies demonstrated a strongly increased magnetic susceptibility followed by thermally assisted magnetization reversal in an external magnetic field.…”