Hamburg 2001 – scientific programme
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TT: Tiefe Temperaturen
TT 25: Postersitzung III: Pinning und Vortexdynamik, Massive HTSL, Bandleiter, Transporteigenschaften in HTSL, SL dünner Filme, Elektronen und Phononen in HTSL, Tunneln, Borkarbide, Quantenphasen und Metall-Isolator-Überg
änge, Anwendungen, Sonstiges
TT 25.48: Poster
Thursday, March 29, 2001, 14:30–17:00, Rang S\ 3
Rare regions in a disordered itinerant quantum antiferromagnet with cubic anisotropy — •Thomas Vojta1 and Rajesh Narayanan2 — 1Institut für Physik, TU Chemnitz, D-09107 Chemnitz, Germany — 2Theoretical Physics, University of Oxford, Oxford, OX3 NP1, UK
We study the quantum phase transition of an itinerant antiferromagnet with cubic anisotropy in the presence of quenched disorder, paying particular attention to the locally ordered spatial regions that form in the Griffiths region. We derive an effective action where these rare regions are described in terms of static annealed disorder. A one loop renormalization group analysis of the effective action shows that for order parameter dimensions p<4 the rare regions destroy the conventional critical behavior, and the renormalized disorder flows to infinity. For order parameter dimensions p>4 the critical behavior is not influenced by the rare regions, it is described by the conventional dirty cubic fixed point. We also discuss the influence of the rare regions on the fluctuation-driven first-order transition in this system.