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Universal Prethermal Dynamics in Heisenberg Ferromagnets
Saraswat Bhattacharyya1, Joaquin F Rodriguez-Nieva1, Eugene Demler1
1Department of Physics, Harvard University, Cambridge, Massachusetts 02138, USA.
Physical Review Letters
|December 18, 2020
Summary
Magnons in magnetic materials show universal scaling behavior, independent of specific details. This distinct dynamics, driven by SU(2) symmetry, offers new insights into quantum systems.
Area of Science:
- Condensed Matter Physics
- Quantum Magnetism
- Statistical Mechanics
Background:
- Understanding far-from-equilibrium dynamics in quantum magnetic systems is crucial for developing novel quantum technologies.
- Prethermal dynamics, a transient state before thermalization, exhibits unique behaviors not seen in equilibrium systems.
- Magnons, the quasiparticles of spin waves in magnetic materials, are key to exploring these dynamics.
Purpose of the Study:
- To investigate the far-from-equilibrium prethermal dynamics of magnons in Heisenberg ferromagnets.
- To identify universal scaling behaviors in the quasiparticle distribution function.
- To elucidate the role of SU(2) symmetry in shaping these dynamics.
Main Methods:
- Utilizing the Boltzmann kinetic equation to compute scaling exponents.
- Simulating dynamics with incoherent initial conditions achievable via microwave magnon pumping.
- Comparing numerical results with analytic estimates and assessing robustness to initial condition variations.
Main Results:
- Demonstrated universal self-similar scaling in momentum and time for the magnon quasiparticle distribution function.
- Identified scaling exponents independent of microscopic details and initial conditions.
- Showcased distinct prethermal dynamics compared to Bose gases, attributed to momentum-dependent magnon-magnon scattering.
Conclusions:
- The SU(2) symmetry in Heisenberg ferromagnets leads to unique prethermal dynamics characterized by universal scaling.
- These findings provide a theoretical framework for experimental verification in various quantum spin systems.
- The study opens avenues for exploring non-equilibrium quantum phenomena in magnetic materials.
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