Dual-pump manipulation of ultrafast demagnetization in TbFeCo

Laser-induced ultrafast demagnetization in TbFeCo has been studied with a dual-pumping system. Five different laser fluence combinations were applied at three different time intervals between two pump pulses. The experimental results are also compared with computational simulations using the atomistic model. Importantly, this demagnetization can be controllably manipulated in both its magnitude and temporal response.

Figure 1

Hysteresis loop of TbFeCo, measured at room temperature.

Figure 2

Schematic diagram of the dual-pumping system.

Figure 3

Reflectivity (a) and demagnetization (b) curves induced by a single pumping system with increasing pump fluence (from 2 to 6.1 $\mathrm{J}/{\mathrm{m}}^2$).

Figure 4

(a) Reflectivity peak as a function of the increasing pump fluence (the red line is linear fit to the data points). (b) Kerr rotation peak as a function of the increasing pump fluence (the red line is a spline line as a guide to the eye).

Figure 5

(a) The reflectivity profile under a pump fluence of 2.6 $\mathrm{J}/{\mathrm{m}}^2$ compared to (b) two-temperature model simulations with the same pump fluence but different mixing factor $\mathbf{\alpha }$. (c) Reflectivities produced by computational simulations with the mixing factor $\mathbf{\alpha }$ as 0.15 (15%). (d) Demagnetizations produced by computational simulations with the mixing factor $\mathbf{\alpha }$ as 0.15 (15%).

Figure 6

(a) Fixed Pump1 (3.3 $\mathrm{J}/{\mathrm{m}}^2$) and variable Pump2 (1, 1.5, and 2 $\mathrm{J}/{\mathrm{m}}^2$) at a time interval of 0.5 ps (experiment). (b) Fixed Pump1 (3.3 $\mathrm{J}/{\mathrm{m}}^2$) and variable Pump2 (1, 1.5, and 2 $\mathrm{J}/{\mathrm{m}}^2$) at a time interval of 0.5 ps (simulation). (c) Fixed Pump1 (3.3 $\mathrm{J}/{\mathrm{m}}^2$) and variable Pump2 (1, 1.5, and 2 $\mathrm{J}/{\mathrm{m}}^2$) at a time interval of 1 ps (experiment). (d) Fixed Pump1 (3.3 $\mathrm{J}/{\mathrm{m}}^2$) and variable Pump2 (1, 1.5, and 2 $\mathrm{J}/{\mathrm{m}}^2$) at a time interval of 1 ps (simulation).

Figure 7

(a) Reflectivity curves induced by dual-pump (4.3 + 1 $\mathrm{J}/{\mathrm{m}}^2$) and (3.3 + 2 $\mathrm{J}/{\mathrm{m}}^2$) at a time interval of 0.5 ps (experiment). (b) Reflectivity curves induced by dual-pump (4.3 + 1 $\mathrm{J}/{\mathrm{m}}^2$) and (3.3 + 2 $\mathrm{J}/{\mathrm{m}}^2$) at a time interval of 0.5 ps (simulation). (c) Reflectivity curves induced by dual-pump (4.3 + 1 $\mathrm{J}/{\mathrm{m}}^2$) and (3.3 + 2 $\mathrm{J}/{\mathrm{m}}^2$) at a time interval of 1 ps (experiment). (d) Reflectivity curves induced by dual-pump (4.3 + 1 $\mathrm{J}/{\mathrm{m}}^2$) and (3.3 + 2 $\mathrm{J}/{\mathrm{m}}^2$) at a time interval of 1 ps (simulation).

Figure 8

(a) Demagnetization induced by dual-pump (4.3 + 1 $\mathrm{J}/{\mathrm{m}}^2$) and (3.3 + 2 $\mathrm{J}/{\mathrm{m}}^2$) at a time interval of 0.5 ps (experiment). (b) Demagnetization induced by dual-pump (4.3 + 1 $\mathrm{J}/{\mathrm{m}}^2$) and (3.3 + 2 $\mathrm{J}/{\mathrm{m}}^2$) at a time interval of 0.5 ps (simulation). (c) Demagnetization induced by dual-pump (4.3 + 1 $\mathrm{J}/{\mathrm{m}}^2$) and (3.3 + 2 $\mathrm{J}/{\mathrm{m}}^2$) at a time interval of 1 ps (experiment). (d) Demagnetization induced by dual-pump (4.3 + 1 $\mathrm{J}/{\mathrm{m}}^2$) and (3.3 + 2 $\mathrm{J}/{\mathrm{m}}^2$) at a time interval of 1 ps (simulation).

Figure 9

Computational simulations with different dual-pump combinations and time intervals. (a) Reflectivity curves induced by dual-pump ($4.3+1, 3.3+2, 2.3+3$, and $1.3+4 \mathrm{J}/{\mathrm{m}}^2$) at a time interval of 0.5 ps. (b) Reflectivity curves induced by dual-pump ($4.3+1, 3.3+2, 2.3+3$, and $1.3+4 \mathrm{J}/{\mathrm{m}}^2$) at a time interval of 1 ps. (c) Demagnetization induced by dual-pump ($4.3+1, 3.3+2, 2.3+3$, and $1.3+4 \mathrm{J}/{\mathrm{m}}^2$) at a time interval of 0.5 ps. (d) Demagnetization induced by dual-pump ($4.3+1, 3.3+2, 2.3+3$, and $1.3+4 \mathrm{J}/{\mathrm{m}}^2$) at a time interval of 1 ps.

Figure 10

(a) Demagnetization induced by dual-pumping system (3.3 + 1 $\mathrm{J}/{\mathrm{m}}^2$) at different time intervals (0, 0.5, and 1 ps) (experiment). (b) Demagnetization induced by dual-pumping system (3.3 + 1 $\mathrm{J}/{\mathrm{m}}^2$) at different time intervals (0, 0.5, and 1 ps) (simulation). (c) Demagnetization induced by dual-pumping system (3.3 + 1.5 $\mathrm{J}/{\mathrm{m}}^2$) at different time intervals (0, 0.5, and 1 ps) (experiment). (d) Demagnetization induced by dual-pumping system (3.3 + 1.5 $\mathrm{J}/{\mathrm{m}}^2$) at different time intervals (0, 0.5, and 1 ps) (simulation).