Berlin 2008 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 19: Correlated Electrons: Quantum-Critical Phenomena

TT 19.13: Vortrag

Dienstag, 26. Februar 2008, 17:30–17:45, H 3010

Dynamical Scaling Properties of a Doped Quantum Heisenberg Antiferromagnet in Two Dimensions — •Marcello Silva Neto, Juergen Falb, and Alejandro Muramatsu — Institut für Theoretische Physik III, Pfaffenwaldring 57, 70550, Stuttgart, Germany

We study the dynamical scaling properties of an effective quantum field theory for the magnetic degrees of freedom of the t−t^′−t^′′−J model, which is believed to be the relevant model for the physics of cuprate superconductors. We find that, at the lowest doping, where the Fermi surface for the doped holes is composed of very small hole pockets at special points in the magnetic Brillouin zone, damping due to the scattering of magnons from particle-hole excitations is absent and the dynamical critical exponent is z=1. As doping increases, however, a nonzero damping term is present. In this case, we find that: i) for the case of Landau damping (clean limit), such term does not modify the dynamical exponent which remains at z=1 for a large portion of the phase diagram, in agreement with experiments; ii) for the case of diffusive damping (dirty limit), such term changes the dynamical exponent from z=1 to 1<z≤ 2, and for even larger doping a crossover to a Fermi liquid regime is expected. We compare our findings to previous discussions available in the literature and we discuss the relevance of our results to the physics of high-Tc superconductors.