Regensburg 2025 – scientific programme
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MA: Fachverband Magnetismus
MA 21: Frustrated Magnets I
MA 21.6: Talk
Wednesday, March 19, 2025, 10:45–11:00, H18
Pseudo-Majorana Functional Renormalization for Frustrated XXZ-Z Spin-1/2 Models — Frederic Bippus1, Benedikt Schneider1, and •Björn Sbierski2 — 1LMU München — 2Universität Tübingen
The numerical study of high-dimensional frustrated quantum magnets remains a challenging problem. Here we present an extension of the pseudo-Majorana functional renormalization group to spin-1/2 XXZ type Hamiltonians with field or magnetization along spin-Z direction at finite temperature. We consider a U(1) symmetry-adapted fermionic spin representation and derive the diagrammatic framework and its renormalization group flow equations. We discuss benchmark results and application to two anti-ferromagnetic triangular lattice materials recently studied in experiments with applied magnetic fields: First, we numerically reproduce the magnetization data measured for CeMgAl11O19 confirming model parameters previously estimated from inelastic neutron spectrum in high fields. Second, we showcase the accuracy of our method by studying the thermal phase transition into the spin solid up-up-down phase of Na2BaCo(PO4)2 in good agreement with experiment.
Keywords: functional renormalization; frustrated quantum magnets; numerical methods