Regensburg 2007 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 31: Low-dimensional Systems - Models I

TT 31.5: Vortrag

Donnerstag, 29. März 2007, 18:45–19:00, H19

Probing anomalous longitudinal fluctuations of the interacting Bose gas via Bose-Einstein condensation of magnons — •Andreas Kreisel, Nils Hasselmann, and Peter Kopietz — Institut für Theoretische Physik, Universität Frankfurt, Max-von-Laue Strasse 1, 60438 Frankfurt, Germany

The emergence of a finite staggered magnetization in quantum Heisenberg antiferromagnets subject to a uniform magnetic field can be viewed as Bose-Einstein condensation of magnons. Using non-perturbative results for the infrared behavior of the interacting Bose gas[1], we present exact results for the staggered spin-spin correlation functions of quantum antiferromagnets in a magnetic field at zero temperature. In particular, we show that in dimensions 1 < D ≤ 3 the longitudinal dynamic structure factor S_∥ (q^→ , ω ) describing staggered spin fluctuations in the direction of the staggered magnetization exhibits a critical continuum, whose weight can be controlled experimentally by varying the magnetic field [2].

[1] F. Pistolesi, C. Castellani, C. Di Castro, and G. C. Strinati, Phys. Rev. B 69, 024513 (2004)

[2] Andreas Kreisel, Nils Hasselmann and P. Kopietz, cond-mat/0610575