Ultrafast unidirectional spin Hall magnetoresistance driven by terahertz light field

Area of Science:

• Condensed matter physics
• Spintronics
• Materials science

Background:

• Ultrafast control of magnetization is crucial for high-speed memory devices.
• Efficient electrical detection of magnetic states at terahertz frequencies remains a challenge.
• Unidirectional spin-Hall magnetoresistance (USMR) offers a promising two-terminal detection geometry.

Purpose of the Study:

• To demonstrate the effectiveness of USMR for ultrafast magnetic state detection at terahertz frequencies.
• To investigate the underlying mechanisms of USMR in ferromagnet/heavy metal heterostructures.
• To explore the potential of USMR for all-electrical detection of terahertz magnon modes.

Main Methods:

• Fabrication of various ferromagnet/heavy metal thin film heterostructures.
• Measurement of USMR via terahertz second-harmonic generation.
• Temperature-dependent measurements of USMR to analyze scattering mechanisms.

Main Results:

• USMR was successfully demonstrated to be effective at terahertz frequencies, enabling picosecond time readouts.
• Ultrafast USMR signals were observed in multiple heterostructures.
• Electron-magnon spin-flip scattering was identified as a significant contributor to USMR.

Conclusions:

• USMR is a viable method for ultrafast electrical detection of magnetic states at terahertz frequencies.
• The findings pave the way for energy-efficient, high-speed magnetic memory technologies.
• USMR holds potential for the all-electrical detection of terahertz magnon modes.