Intrinsic subpicosecond magnetization reversal driven by femtosecond laser pulses in GdFeCo amorphous films

Abstract

Ultrafast magnetization dynamics in GdFeCo films triggered by femtosecond laser pulses with and without an external field applied is studied experimentally for different excitation fluence. It is found that subpicosecond magnetization reversal occurs simultaneously in the ultrafast dynamics of both saturation and remnant magnetization states and almost identical within 13 ps, whereas relatively slow magnetization reversal across compensation point appears only in the dynamics of saturation magnetization state. It shows the subpicosecond magnetization reversal is external field independent, and originates from intrinsic magnetic evolution in ferrimagnetic system. The intrinsic subpicosecond reversal is qualitatively explained by linear reversal.

Ultrafast dynamics of 4f electron spins in TbFeCo film driven by inter-atomic 3d–5d–4f exchange coupling

“…Ultrafast spin dynamics in magnetic system has been an important and active field due to its scientific significance and great potential for developing new magnetic and spintronic technologies [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20]. Many researches concentrated on the rare earth (RE) metals [20][21][22][23][24][25], in which the magnetism mainly comes from the localized 4f electrons.…”

“…It seemed to suggest that in RE metals the intra-atomic 5d-4f spin-spin coupling cannot directly drive the demagnetization of 4f spins. On the other hand, ultrafast spin dynamics in rare earth-transition metal (RE-TM) ferrimagnetic alloys has also attracted much more attentions due to the significant potential applications of RE-TM alloys [2][3][4][5][6][7][8][9][10][11][12][13][14][15][16], particularly in ultrafast magnetic recording [2][3][4][5][6][7][8][9][10][11][12]. By means of TR-XMCD, Radu et al have demonstrated the ultrafast magnetization reversal dynamics of the RE and TM components in a GdFeCo film under an excitation of 800 nm fs laser [2].…”

Effect of laser pulse propagation on ultrafast magnetization dynamics in a birefringent medium

“…Efforts to find new, faster ways of manipulating the magnetic states of media have yielded spectacular and unexpected results over the past two decades [1][2][3]. Experiments showed that femtosecond laser pulses can trigger a variety of (sub)picosecond changes in magnetic materials, including ultrafast demagnetization [4][5][6]; coherent spin deflection followed by homogeneous precession [7] and spin waves [8,9]; various phase transitions resulting in the emergence of magnetization [10][11][12][13] or its reorientation [14,15]; emergence of non-equilibrium magnetic states [16]; complete magnetization reversal [17][18][19][20][21][22][23][24]; spin transport [6,25,26]; and even modification of exchange interactions [27]. As these laser-induced events are 100 to 1000 times faster than the elementary operations in currently used magnetic recording devices, a study of ultrafast magnetism can facilitate new technologies for ever faster recording and processing of magnetically stored information.…”