Berlin 2024 – scientific programme
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MA: Fachverband Magnetismus
MA 27: Frustrated Magnets I
MA 27.11: Talk
Wednesday, March 20, 2024, 17:45–18:00, H 2013
Constructing Emergent U(1) Symmetries in the Gamma-Prime model — •Sagar Ramchandani1, Simon Trebst1, and Ciarán Hickey1,2,3 — 1Institute for Theoretical Physics, University of Cologne — 2School of Physics, University College Dublin, Belfield, Dublin — 3Centre for Quantum Engineering, Science, and Technology, University College Dublin
Frustrated magnets can elude the paradigm of spontaneous symmetry breaking and exhibit emergent symmetries at low temperatures. Here we study such an emergent symmetry in a classical spin model whose underlying Hamiltonian actually has very little symmetry, a bond-directional, off-diagonal exchange model inspired by the microscopics of spin-orbit entangled materials (the Gamma-prime model). Surprisingly, the ground state possesses an emergent, continuous U(1) symmetry for a wide variety of lattice geometries with triangular motifs, such as the kagome or hyperkagome lattices. We discuss a thermal order-by-disorder effect which leads to the formation of a Z6 symmetric phase at the lowest temperatures. Using Monte Carlo simulations, we explore the model’s full finite temperature phase diagram and connect its dependence on spatial dimension (2d versus 3d) to known renormalization group results. Finally we comment on the fate of the model in the quantum spin-1/2 limit.
Keywords: Emergent Symmetry; Spin-orbit coupled magnets; Gamma-Prime model; Order-by-disorder; Kagome