Berlin 2008 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 24: Correlated Electrons: Low-dimensional Systems - Models

TT 24.11: Vortrag

Mittwoch, 27. Februar 2008, 16:45–17:00, H 2053

Hybrid approach for quantum antiferromagnets in a uniform magnetic field: Application — •Francesca Sauli, Andreas Kreisel, Nils Hasselmann, and Peter Kopietz — Institut für Theoretische Physik, Universität Frankfurt, Max-von-Laue Strasse 1, 60438 Frankfurt, Germany

We use a hermitian parameterization of the canonical magnon operators obtained from the usual Holstein-Primakoff transformation and combine it with a 1/S-expansion of the Heisenberg model to acquire the effective action for quantum antiferromagnets (QAF). Integrating over the fields associated with the uniform spin fluctuations yields a field theory for the staggered spin fluctuations on a lattice but avoids the cutoff ambiguities of the non-linear sigma model (NLSM). Using this effective lattice action for the staggered spin-fluctuations of a QAF subject to a uniform magnetic field we explicitly calculate the leading 1/S-corrections to the spin wave velocity as well as the damping of the staggered spin fluctuations.