Real-time Hall-effect detection of current-induced magnetization dynamics in ferrimagnets

Hall effects are ubiquitous in electronic systems and are essential tools for studying the physics of condensed-matter systems and spintronic devices. However, the real-time detection of their dynamics has been impeded by the inherent small magnitude of the Hall signals.

Here we present a novel concept to perform time-resolved measurements of Hall and transverse magnetoresistance signals. Our approach achieves the signal quality necessary for the single-shot detection with a resolution <100 ps. This capability is unique to our technique since standard pump-probe schemes can sense only the reproducible dynamics.

By performing time-resolved anomalous Hall effect measurements we studied the magnetization switching induced by spin-orbit torques in ferrimagnetic GdFeCo [1]. We found that the dynamics comprises a fast reversal (>1 km/s), as typical of ferrimagnets [2,3], and a long, unexpected incubation phase. Both phases show stochastic fluctuations of thermal origin. Overall, the measurements demonstrate the potential of this new technique for investigating the current-induced dynamics of Hall effects with single-shot sensitivity.

[1] A. Manchon et al., Rev. Mod. Phys. 91, 035004 (2019)
[2] L. Caretta et al., Nat. Nano. 13, 1154 (2018)
[3] K. Cai et al., Nat. Electr. 3, 1187 (2020)