Related Experiment Video
Updated: Jul 17, 2025
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Measurement of Coherence Decay in GaMnAs Using Femtosecond Four-wave Mixing
Published on: December 3, 2013
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Picosecond spin-orbit torque-induced coherent magnetization switching in a ferromagnet
Debanjan Polley1,2,3, Akshay Pattabi2,4, Ashwin Rastogi2
1Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA 94720, USA.
Science Advances
|September 6, 2023
Summary
Researchers demonstrated ultrafast spin-orbit torque (SOT) for rapid magnetic memory switching. This novel method uses a ~9-picosecond electrical pulse for coherent magnetization dynamics, paving the way for faster SOT magnetic random-access memory.
Area of Science:
- Spintronics
- Materials Science
- Electrical Engineering
Background:
- Nonvolatile magnetic memories offer potential alternatives to conventional semiconductor technologies.
- Spin-orbit torque (SOT) is a key mechanism for electrical control of magnetism.
Purpose of the Study:
- To experimentally demonstrate ultrafast spin-orbit torque (SOT)-induced coherent magnetization switching dynamics.
- To investigate magnetization dynamics with sub-picosecond resolution using ultrafast electrical pulses.
Main Methods:
- Generation and guidance of a ~9-picosecond electrical pulse using an ultrafast photoconducting switch and coplanar strip line.
- Induction of ultrafast SOT in a heavy metal/ferromagnet multilayer.
- Magneto-optical probing for sub-picosecond resolution analysis of magnetization dynamics.
Main Results:
- Observed coherent magnetization switching dynamics.
- Achieved zero-crossing of magnetization in ~70 picoseconds, driven by combined thermal anisotropy and damping-like torques.
- Macro-magnetic simulations coupled with ultrafast heating models validated experimental findings.
Conclusions:
- Demonstrated a unique magnetization switching mechanism enabling coherent rotation.
- Achieved unprecedented switching speeds without incubation delay.
- Proposed a method to significantly increase the writing speed of SOT magnetic random-access memory devices.
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