Regensburg 2004 – scientific programme

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TT: Tiefe Temperaturen

TT 21: Quantenkritische Ph
änomene

TT 21.3: Talk

Wednesday, March 10, 2004, 17:15–17:30, H18

Dynamical CPA approach to an itinerant fermionic spin glass model — •Michael Bechmann and Reinhold Oppermann — Institut für Theoretische Physik und Astrophysik, Universität Würzburg, Am Hubland, 97074 Würzburg

We study a fermionic version of the Sherrington-Kirkpatrick model including nearest-neighbor hopping on a ∞-dimensional simple cubic lattices. The problem is reduced to one of free fermions moving in a dynamical effective random medium. By means of a CPA method we derive a set of self-consistency equations for the spin glass order parameter and for the Fourier components of the local spin susceptibility. In order to solve these equations numerically we employ an approximation scheme which restricts the dynamics to a feasible number of the leading Fourier components. From a sequence of systematically improved dynamical approximations we estimate the location of the quantum critical point.