Exchange-driven all-optical magnetic switching in compensated 3d ferrimagnets

Abstract

Understanding how a single laser pulse can toggle magnetization in a compensated 3d ferrimagnet is a critical problem in ultrafast magnetism. To resolve it, we test single-shot all-optical switching of magnetization in Mn 2 Ru x Ga at different temperatures using femto-to picosecond pulses in the visible to far-infrared spectral ranges. The switching process is found to be independent of photon energy, but strongly dependent on both the pulse duration and sample temperature. Switching is disabled whenever the starting temperature T 0 is above the compensation point of Mn 2 Ru x Ga, but as T 0 is lowered below compensation, increasingly longer pulses become capable of toggling the magnetization. We explain the observations in terms of a switching process driven by exchange relaxation of the angular momenta of the manganese sublattices, and propose a common framework to account for the similarities and differences of all-optical switching in Mn 2 Ru x Ga and GdFeCo alloys.

Ultrafast demagnetization in a ferrimagnet under electromagnetic field funneling

“…This suggests that the use of nanoplasmon optics could make AOS technologically viable by making the attainable bit size comparable to that, for example, of heat-assisted magnetic recording 13 . The so far revealed mechanism behind AOS implies that it proceeds via fast and efficient demagnetization 6,[14][15][16] . Therefore, a crucial step towards achieving nanoplasmonic AOS is to follow the temporal evolution of the magnetization in response to plasmon nanoantenna-assisted resonant laser excitation.…”

Spin-transport Mediated Single-shot All-optical Magnetization Switching of Metallic Films

“…The mechanism of single-shot AOS in Mn 2 RuGa is similar to that of GFC, although switching was realized only when the initial temperature was below the magnetization compensation temperature of Mn 2 RuGa. 45) Single-shot AOS is of purely thermal origin; therefore, magnetization switching can be induced by ultrashort electrical pulses and has garnered significant attention for future ultrafast spintronics devices. Magnetization switching triggered by electrical pulses has been reported in several studies.…”

“…30,[32][33][34][35][36][37][38][39] Single-shot AOS of GFC is mediated by the transient ferromagnetic state owing to the angular momentum transfer between the two sublattices. 40,41) Although several studies have demonstrated single-shot AOS in Tb-based RE-TM system such as TbFeCo alloy, 42) [Tb=Co] multilayer 43) and ferrimagnetic Heusler alloy Mn 2 Ru x Ga, 44,45) single-shot AOS has been primarily inves- tigated using Gd-based materials including synthetic ferrimagnets such as Co=Gd. [46][47][48] Whereas many studies on single-shot AOS have been performed on ferrimagnetic thin films, single-shot AOS for FMs has been considered difficult.…”

“…Mn 2 RuGa film on MgO single crystal sub. Inequivalent sublattices of two Mn atoms Banerjee et al44) Mn 2 Ru 0.8 Ga(32), Mn 2 Ru 0.75 Ga(18) on MgO sub.Temperature and pulse duration dependence Davies et al45)…”

Polarisation-dependent single-pulse ultrafast optical switching of an elementary ferromagnet

“…The technological potential of this discovery was quickly recognised, leading to proof-of-concept experiments in connection with information storage [2][3][4] . Such laser-driven magnetisation dynamics has also been explored in bulk rare-earth ferromagnets 5 , in ferrimagnets 2,[6][7][8][9][10][11][12][13] , and in ferromagnetic thin films 3,[14][15][16][17][18][19][20] . The underlying physical picture is not yet fully understood, given the diversity of mechanisms that can contribute to or influence the dynamics on distinct or overlapping time scales [21][22][23] .…”