Peter Kopietz

Persistent spin currents in mesoscopic Heisenberg rings

We show that at low temperatures T an inhomogeneous radial magnetic field with magnitude B gives rise to a persistent magnetization current around a mesoscopic ferromagnetic Heisenberg ring. Under optimal conditions, this spin current can be as large as gmicro(B)(T/ variant Plancks over 2pi )exp([-2pi(gmicro(B)B/delta)(1/2)], as obtained from leading-order spin-wave theory. Here g is the gyromagnetic factor, micro(B) is the Bohr magneton, and delta is the energy gap between the ground-state and the first spin-wave excitation. The magnetization current endows the ring with an electric dipole moment.

Bosonization of interacting fermions in arbitrary dimension beyond the Gaussian approximation.

We use our recently developed functional bosonization approach to bosonize interacting fermions in arbitrary dimension

Brillouin light scattering spectroscopy of parametrically excited dipole-exchange magnons

d

Universal persistent currents in mesoscopic metal rings due to long-range Coulomb interactions.

beyond the Gaussian approximation. Even in

Wide-range wavevector selectivity of magnon gases in Brillouin light scattering spectroscopy.

d=1

Renormalization of the BCS-BEC crossover by order-parameter fluctuations

the finite curvature of the energy dispersion at the Fermi surface gives rise to interactions between the bosons. In higher dimensions scattering processes describing momentum transfer between different patches on the Fermi surface (around-the-corner processes) are an additional source for corrections to the Gaussian approximation. We derive an explicit expression for the leading correction to the bosonized Hamiltonian and the irreducible self-energy of the bosonic propagator that takes the finite curvature as well as around-the-corner processes into account. In the special case that around-the-corner scattering is negligible, we show that the self-energy correction to the Gaussian propagator is negligible if the dimensionless quantities

Collective fields in the functional renormalization group for fermions, Ward identities, and the exact solution of the Tomonaga-Luttinger model

( \frac{q_{c} }{ k_{F}} )^d F_{0} [ 1 + F_{0} ]^{-1} \frac{\mu}{\nu^{\alpha}} | \frac{ \partial \nu^{\alpha} }{ \partial \mu} |

Magnetoelastic modes and lifetime of magnons in thin yttrium iron garnet films

are small compared with unity for all patches

ANOMALOUS SCALING AND SPIN-CHARGE SEPARATION IN COUPLED CHAINS

\alpha

Spectral function and quasiparticle damping of interacting Bosons in two dimensions.

. Here