134 citations · 368 across the 14 of their papers we have counts for
15 papers
Functional renormalization group in an external field: constant field versus constant order parameter
Julia von Rothkirch, Andreas Rückriegel, Peter Kopietz
Renormalization group (RG) flows for systems subject to an external field can be derived either by fixing the field or by fixing the conjugate order parameter. We show how to imple…
Bad Metal Behavior and Lifshitz Transition of a Nagaoka Ferromagnet
Jonas Arnold, Peter Kopietz, Andreas Rückriegel
Using an extension of the fermionic functional renormalization group for systems where strong correlations give rise to projected Hilbert spaces we calculate the phase diagram and…
Phase diagram of the - quantum Heisenberg model for arbitrary spin
Andreas Rückriegel, Dmytro Tarasevych, Peter Kopietz
We use the spin functional renormalization group to investigate the - quantum Heisenberg model on a square lattice. By incorporating sum rules associated with the fixed l…
Non-Fermi liquid fixed point of the dissipative Yukawa-Sachdev-Ye-Kitaev model
Niklas Cichutek, Andreas Rückriegel, Peter Kopietz
Using a functional renormalization group approach we derive the renormalization group (RG) flow of a dissipative variant of the Yukawa-Sachdev-Ye-Kitaev model describing fermio…
Functional renormalization group without functional integrals: implementing Hilbert space projections for strongly correlated electrons via Hubbard X-operators
Andreas Rückriegel, Jonas Arnold, Rüdiger Krämer +1
Exact functional renormalization group (FRG) flow equations for quantum systems can be derived directly within an operator formalism without using functional integrals. This simple…
Spin functional renormalization group for the quantum Heisenberg model
Dmytro Tarasevych, Andreas Rückriegel, Savio Keupert +2
We use our recently developed functional renormalization group (FRG) approach for quantum spin systems to investigate the phase diagram of the frustrated quantum…
Spin functional renormalization group for dimerized quantum spin systems
Andreas Rückriegel, Jonas Arnold, Raphael Goll +1
We investigate dimerized quantum spin systems using the spin functional renormalization group approach proposed by Krieg and Kopietz [Phys. Rev. B 99, 060403(R) (2019)] which direc…
Accumulation of magnetoelastic bosons in yttrium iron garnet: kinetic theory and wave vector resolved Brillouin light scattering
Viktor Hahn, Pascal Frey, Alexander A. Serga +4
We derive and solve quantum kinetic equations describing the accumulation of magnetoelastic bosons in an overpopulated magnon gas realized in a thin film of the magnetic insulator…
Green's function formalism for nonlocal elliptical magnon transport
W. P. Sterk, Andreas Rückriegel, H. Y. Yuan +2
We develop a non-equilibrium Green's function formalism to study magnonic spin transport through a strongly anisotropic ferromagnetic insulator contacted by metallic leads. We mode…
Bulk and edge spin transport in topological magnon insulators
Andreas Rückriegel, Arne Brataas, Rembert A. Duine
We investigate the spin transport properties of a topological magnon insulator, a magnetic insulator characterized by topologically nontrivial bulk magnon bands and protected magno…
Spin currents, spin torques, and the concept of spin superfluidity
Andreas Rückriegel, Peter Kopietz
In magnets with non-collinear spin configuration the expectation value of the conventionally defined spin current operator contains a contribution which renormalizes an external ma…
Rayleigh-Jeans condensation of pumped magnons in thin film ferromagnets
Andreas Rückriegel, Peter Kopietz
We show that the formation of a magnon condensate in thin ferromagnetic films can be explained within the framework of a classical stochastic non-Markovian Landau-Lifshitz-Gilbert…
Non-perturbative renormalization group calculation of the quasi-particle velocity and the dielectric function of graphene
Carsten Bauer, Andreas Rückriegel, Anand Sharma +1
Using a non-perturbative functional renormalization group approach we calculate the renormalized quasi-particle velocity and the static dielectric function of susp…
Magneto-elastic modes and lifetime of magnons in thin yttrium-iron garnet films
Andreas Rückriegel, Peter Kopietz, Dmytro A. Bozhko +2
We calculate the effects of the spin-lattice coupling on the magnon spectrum of thin ferromagnetic films consisting of the magnetic insulator yttrium-iron garnet. The magnon-phonon…
Time-dependent spin-wave theory
Andreas Rückriegel, Andreas Kreisel, Peter Kopietz
We generalize the spin-wave expansion in powers of the inverse spin to time-dependent quantum spin models describing rotating magnets or magnets in time-dependent external fields.…