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VIDEO DOI: https://doi.org/10.48448/ybck-w103

technical paper

MMM 2022

November 07, 2022

Minneapolis, United States

Ultralow power nanosecond spin orbit torque magnetization switching induced by BiSb topological insulator

We demonstrate spin orbit torque (SOT) magnetization switching of (Pt/Co) multilayers with large perpendicular magnetic anisotropy (PMA) by a topological insulator Bi0.85Sb0.15 layer in both thermal activation and non-thermal regime with current pulse width τ down to 1 ns. For this purpose, we deposited a stack of Bi0.85Sb0.15(10 nm)/Pt(0.4 nm)/Co(0.4 nm)2/insulating buffer on a Si/SiOx substrate by magnetron sputtering, as shown in Fig. 1(a). The (Pt/Co) multilayers have a large PMA with anisotropy magnetic field of 6 kOe. We then fabricated 1000 nm × 800 nm Hall bar devices for ultrafast SOT switching measurement. Figure 1 (b) shows the threshold switching current density JBiSbth as a function of τ at Hx = 1 kOe. The red dashed line is fitting by the thermal activation model (τ >> 10 ns), which yields a zero-Kelvin JBiSbth0 = 2.5×106 A/cm2. Meanwhile, the green dashed line is fitting for the non-thermal regime (τ < 10 ns), which yields a larger JBiSbth0 = 4.1×106 A/cm2 but still smaller than those observed in heavy metals by nearly two orders of magnitude. Figure 1(c) shows SOT switching loops at various t from 4 ns to 1 ns. From time-resolved measurement using 1 ns pulses, we observed a fast domain wall velocity of 470 m/s at a modest JBiSb =1.6×107 A/cm2. We then successfully demonstrated deterministic SOT switching in our device by multi pulses (JBiSb =1.3×107 A/cm2, τ = 3 ns) at Hx = -1 kOe and +1 kOe as shown in Fig. 2. These results demonstrate the potential of BiSb topological insulator for ultralow power and ultrafast operation of SOT-based spintronic devices 1,2.

References 1 N. H. D. Khang, et al, Nature Mater. 17, 808 (2018). 2 N. H. D. Khang, et al, Appl. Phys. Lett. 120, 152401 (2022).


Transcript English (automatic)

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