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Frustrated three dimensional quantum magnets bear a rich phenomenology but are notoriously hard to treat theoretically. We show how a Majorana representation of spin operators, in combination with the functional renormalization group allows for quantiative simulations at finite temperatures. Focusing on Heisenberg magnets, we establish a finite-size scaling approach and extract accurate results for critical temperatures and -exponents. Further, we quantify and discuss the improvements introduced by two-loop contributions in the flow equations applied to the Pyrochlore lattice. We then investigate the accuracy of its prominent spin-ice rule under the influence of both quantum and thermal fluctuations.

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Nils Niggemann, FU Berlin
Seminarraum Altbau Theorie
Contact: Dominik Kiese