Strong Spin-Phonon Coupling Mediated by Single Ion Anisotropy in the All-In-All-Out Pyrochlore Magnet...

Area of Science:

• Condensed Matter Physics
• Materials Science
• Magnetism

Background:

• Spin-phonon coupling is crucial for understanding magnetic materials.
• Single ion anisotropy plays a key role in magnetic properties.
• Cd_{2}Os_{2}O_{7} is an all-in-all-out pyrochlore magnet with strong spin-orbit coupling.

Purpose of the Study:

• To investigate spin-phonon coupling mediated by single ion anisotropy in Cd_{2}Os_{2}O_{7}.
• To elucidate the role of spin-orbit coupling in magnetoelastic effects.
• To establish a new type of spin-phonon coupling mechanism.

Main Methods:

• Optical spectroscopy was employed to probe phonon behavior.
• First-principles calculations were utilized to model the material's properties.
• Analysis focused on phonon frequencies and linewidths around the magnetic ordering temperature.

Main Results:

• Observed significant anomalies in phonon frequencies and linewidths at the magnetic ordering temperature.
• Demonstrated exceptionally large renormalization of phonon modes.
• Established a strong correlation between phonon frequency shifts and crystal field modulation.

Conclusions:

• A new type of spin-phonon coupling via single ion anisotropy, a second-order spin-orbit coupling term, was identified in Cd_{2}Os_{2}O_{7}.
• The findings highlight an unconventional magnetoelastic term arising from strong spin-orbit coupling.
• This study provides fundamental insights into the interplay between lattice dynamics and magnetism in complex materials.