Regensburg 2025 – scientific programme

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MA: Fachverband Magnetismus

MA 15: Poster I

MA 15.5: Poster

Tuesday, March 18, 2025, 10:00–12:30, P1

Dynamical Mean Field Theory for Spin Systems at Finite Temperature — •Przemysław Bieniek, Timo Gräßer, and Götz Uhrig — Technische Universität Dortmund, Fakultät Physik

In the recent years, a dynamical mean field theory approach for spin systems at infinite temperature (spinDMFT) was developed. It is an approximate technique in the limit of an infinite coordination number, reducing the full dynamics of a spin system to a problem of a single spin interacting with a dynamical environment field. This allows for very efficient computation of spin correlations, which shows good agreement with other computational techniques and excellently describes nuclear magnetic resonance (NMR) experiments.

However, the current version of spinDMFT applies only to systems at infinite temperature and two-site couplings. We aim at extending the technique. One goal is to address finite temperatures, but still above any ordering temperature. To this end, we modify the approach to dynamical Green's functions instead of spin correlations. The second goal is to deal with three-site couplings as they arise in experiments with magic angle spinning. We benchmark the developed techniques for various spin models by comparing the results with other numerical approaches and discuss possible applications.

Keywords: Disordered spin systems; Mean field theory; Computational techniques; Nuclear magnetic resonance