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TT: Fachverband Tiefe Temperaturen

TT 46: Frustrated Magnets: Spin Liquids

TT 46.13: Vortrag

Donnerstag, 30. März 2023, 12:45–13:00, HSZ 201

Spin-Peierls instability of the U(1) Dirac spin liquid — •Josef Willsher¹, Urban Seifert², and Johannes Knolle^1,3,4 — ¹TU Munich, Germany — ²Kavli Institute, University of California, Santa Barbara, USA — ³MCQST, Munich, Germany — ⁴Imperial College London, UK

Quantum spin liquids are tantalising phases of quantum matter, but experimental evidence of their existence has remained elusive. Recent theoretical and numerical studies have provided evidence that triangular-lattice Heisenberg magnets may host a U(1) Dirac spin liquid (DSL): a state of matter whose low-energy description is given by compact quantum electrodynamics in 2+1 dimensions coupled to four Dirac fermions, which is believed to flow to a strongly interacting conformal fixed point. Monopole operators constitute a strongly relevant perturbation to this fixed point, driving the spin liquid into magnetically ordered or VBS states, but are forbidden by the microscopic (UV) symmetries on the triangular lattice. However, in this work we show that a coupling between certain monopoles and phonons is symmetry-allowed and produces a 2+1-dimensional analog of the spin-Peierls instability for a spin liquid. We study monopole-phonon interactions within a conformal field theory framework and show that the DSL state is generically unstable to a static deformation, precipitating VBS ordering. Finally, we discuss implications for experimental realisations and signatures of the DSL in real 2D materials by addressing a full dynamical quantum model of phonons; here we predict a weak-coupling regime within which the spin-liquid phase remains stable.