Photoinduced spin dynamics in a uniaxial intermetallic heterostructure

Area of Science:

• Condensed Matter Physics
• Materials Science
• Ultrafast Optics

Background:

• Intermetallic heterostructures of rare-earth and transition metals offer unique physical properties.
• These materials exhibit giant magnetostriction, controllable magnetic anisotropy, and magneto-optical activity.
• Spin reorientation transitions (SRT) can be induced by magnetic fields at room temperature.

Purpose of the Study:

• Investigate spin dynamics in rare-earth and transition metal heterostructures.
• Study ultrafast optical excitation effects on spin behavior near SRT.
• Analyze time-resolved light polarization rotation to understand spin dynamics.

Main Methods:

• Utilized ultrafast optical excitation with a 35 fs pump pulse.
• Measured time-dependent light polarization rotation.
• Applied external DC magnetic fields to induce and probe SRT.

Main Results:

• Observed hysteretic polarization rotation dependence on the magnetic field near SRT.
• Found enhanced rotation at critical points of SRT and magnetization switching.
• Identified two characteristic time delays (20 ps and 200 ps) in polarization rotation.

Conclusions:

• The observed hysteretic behavior is characteristic of spin dynamics near SRT.
• The 20 ps delay is attributed to out-of-plane spin precession.
• The 200 ps delay corresponds to in-plane spin deviation and thermal relaxation of anisotropy.