Photoinduced Switching of Magnetization in the Epsilon-Near-Zero Regime

Area of Science:

• Condensed matter physics
• Materials science
• Optics

Background:

• Midinfrared laser pulses can induce magnetization switching in magnetic dielectrics.
• The precise mechanisms, involving lattice excitations, heating, and strain, are not fully understood.
• Understanding these mechanisms is crucial for developing advanced magnetic materials and devices.

Purpose of the Study:

• To investigate the response of magnetic domains in cobalt-doped yttrium iron garnet to midinfrared laser pulses.
• To elucidate the role of optical phonon frequencies and epsilon-near-zero (ENZ) points in magnetization switching.
• To explore methods for controlling magnetization switching through optical field engineering.

Main Methods:

• Experimental study of labyrinthine magnetic domain transformation under midinfrared laser pulses.
• Micromagnetic calculations to explain the observed domain structure changes.
• Electromagnetic calculations to analyze optical field penetration and energy deposition.

Main Results:

• Observed transformation of labyrinthine domains into stable parallel stripes.
• Micromagnetic calculations supported this by showing partial quenching of magnetic anisotropy.
• Magnetization switching efficiency was spectrally strongest at epsilon-near-zero (ENZ) points, not peak absorption.
• ENZ condition led to homogeneous energy deposition due to uniform optical field penetration.

Conclusions:

• Magnetization switching in magnetic dielectrics can be controlled by engineering optical field distribution.
• The epsilon-near-zero (ENZ) condition optimizes spatial optical absorption for efficient magnetization switching.
• This research offers a novel pathway for controlling magnetic properties using tailored optical fields.