Ultrafast demagnetization in a ferrimagnet under electromagnetic field funneling

Area of Science:

• Materials Science
• Optics
• Nanotechnology

Background:

• Improving magnetic memory storage requires faster, more energy-efficient methods.
• Ultrafast optical manipulation of magnetism is crucial for next-generation data storage.
• Nanoscale confinement of magnetic elements remains a significant challenge for miniaturization.

Purpose of the Study:

• To investigate nanoscale confinement of demagnetization dynamics in ferrimagnetic alloys.
• To explore the use of plasmon nanoantennas for optically manipulating magnetism at the ultrafast timescale.
• To demonstrate reduced demagnetization through resonant energy funneling.

Main Methods:

• Employing resonant electromagnetic energy funneling via plasmon nanoantennas.
• Utilizing femtosecond optical pumping on a ferrimagnetic TbCo alloy thin film.
• Comparing demagnetization under resonant versus non-resonant illumination.

Main Results:

• Ag nanoring antennas reduced film demagnetization by up to three times under resonant pumping.
• Nanoscale confinement of the demagnetization process was observed.
• Electromagnetic simulations confirmed resonant optical energy funneling into the film.

Conclusions:

• Plasmon nanoantennas enable nanoscale confinement of ultrafast demagnetization.
• This technique is a significant step towards deterministic ultrafast all-optical magnetization switching at the nanoscale.
• Opens new avenues for developing nanoscale ultrafast magneto-optics and advanced magnetic memory.