Re-order parameter of interacting thermodynamic magnets

Area of Science:

• Condensed Matter Physics
• Materials Science
• Magnetism

Background:

• Traditional phase diagrams rely on static order parameters, which struggle to identify subtle phase transitions like re-ordering.
• Interacting magnets exhibit complex magnetic phases that are challenging to characterize using conventional methods.

Purpose of the Study:

• To develop and apply a dynamic nonequilibrium order parameter, the re-order parameter, for detecting subtle magnetic phases and transitions.
• To investigate the magnetic phase diagram of orthoferrites, specifically YFeO3 and its Mn-doped variations, using magnon dynamics.

Main Methods:

• Introduced a novel dynamic nonequilibrium order parameter termed the 're-order parameter'.
• Utilized low-energy magnons (dynamical precession of magnetization) as a reliable re-order parameter in spin-orbit coupled magnets.
• Employed terahertz emission spectroscopy to probe magnetic structures and transitions in Mn-doped YFeO3.

Main Results:

• Magnon dynamics revealed spin-orbit coupling-induced subtle magnetic structures, leading to distinct terahertz emissions.
• The temporal and spectral characteristics of magnon emission mirrored BCS-type order parameters.
• Successfully constructed the magnetic phase diagram for Mn-doped YFeO3.
• Uncovered a previously concealed ferrimagnetic phase within the Γ1 state.

Conclusions:

• The dynamic re-order parameter, based on magnon precession, is effective for identifying subtle magnetic phases and transitions.
• This approach provides a powerful tool for completing phase diagrams and discovering hidden phases in materials.
• The study demonstrates the potential of magnon emission for characterizing complex magnetic systems.