Nonvolatile phase-programmable spintronic terahertz emitter via laser-induced spin polarization switching.

Area of Science:

• Physics
• Materials Science
• Optics

Background:

• Ultrafast-laser-driven spintronic terahertz (STE) emitters generate efficient ultrabroadband THz radiation.
• These emitters are crucial for future THz technologies and functional THz devices.

Purpose of the Study:

• To realize nonvolatile phase encoding in an IrMn3/Co20Fe60B20/W heterostructure.
• To demonstrate robust THz phase reversal and optical-THz spatial phase patterning.

Main Methods:

• Femtosecond laser excitation with fluence control.
• Time-resolved double-pump experiments to analyze THz phase switching dynamics.
• Optical writing and magnetic reset for reversible phase state manipulation.

Main Results:

• Demonstrated THz phase reversal at a threshold of 0.78 mJ/cm², attributed to spin-polarization reversal.
• Identified a 15 ps thermal gating window for THz phase switching.
• Achieved reversible phase states with >140% contrast over 30 cycles and spatial patterning with 53 dB SNR and 160% contrast.

Conclusions:

• This work enables write-read-reset THz pattern and information encoding.
• Advances the integration of spintronic terahertz emitters with on-chip photonic architectures.