Thermalization of magnons in yttrium-iron garnet: nonequilibrium functional renormalization group approach
arXiv:1206.6689 · doi:10.1103/PhysRevB.86.184417
Abstract
Using a nonequilibrium functional renormalization group (FRG) approach we calculate the time evolution of the momentum distribution of a magnon gas in contact with a thermal phonon bath. As a cutoff for the FRG procedure we use a hybridization parameter Λ giving rise to an artificial damping of the phonons. Within our truncation of the FRG flow equations the time evolution of the magnon distribution is obtained from a rate equation involving cutoff-dependent nonequilibrium self-energies, which in turn satisfy FRG flow equations depending on cutoff-dependent transition rates. Our approach goes beyond the Born collision approximation and takes the feedback of the magnons on the phonons into account. We use our method to calculate the thermalization of a quasi two-dimensional magnon gas in the magnetic insulator yttrium-iron garnet after a highly excited initial state has been generated by an external microwave field. We obtain good agreement with recent experiments.
16 pages, 6 figures, final version
References in corpus (13)
- Exact evolution equation for the effective potential
- From Kadanoff-Baym dynamics to off-shell parton transport
- A perturbative nonequilibrium renormalization group method for dissipative quantum mechanics: Real-time RG in frequency space (RTRG-FS)
- Nonthermal fixed points and the functional renormalization group
- Functional renormalisation group approach to far-from-equilibrium quantum field dynamics
- Microscopic spin-wave theory for yttrium-iron garnet films
- Collective fields in the functional renormalization group for fermions, Ward identities, and the exact solution of the Tomonaga-Luttinger model
- Strong versus weak wave-turbulence in relativistic field theory
- Far-from-equilibrium quantum many-body dynamics
- Elastic constants and ultrasonic attenuation in the cone state of the frustrated antiferromagnet Cs_2CuCl_4
- Bose-Einstein condensation at finite momentum and magnon condensation in thin film ferromagnets
- Field-dependence of magnon decay in yttrium iron garnet thin films
- Non-equilibrium time evolution of bosons from the functional renormalization group
Cited by in corpus (4)
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- Fröhlich versus Bose-Einstein Condensation in Pumped Bosonic Systems
- Bose-Einstein condensation of magnons in spin pumping systems