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arXiv · 2412.08709

Topology-driven deconfined quantum criticality in magnetic bilayers

Sondre Duna Lundemo·Flavio S. Nogueira·Asle Sudbø
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Abstract

Two-dimensional quantum antiferromagnets are believed to host phases of matter whose excitations are more fundamental than those of the ordered phases. When combining two such spin systems in a bilayer, strong interaction between the emergent excitations can produce phases not realized in either of its subsystems. We show that the critical fluctuations of a two-dimensional spin liquid state can induce a deconfined quantum critical point in a proximate antiferromagnet. The most relevant coupling between the associated effective field theories is given by a mixed Chern-Simons term of the emergent gauge fields in each layer. This describes a topological current-current interaction. In contrast to the local spin-spin interaction, it strongly modifies the renormalization group flow of the theory describing the N\'eel-valence-bond-solid transition of the antiferromagnet. In particular, the protected coupling constant associated with it implies non-trivial quantum critical scaling characterized by a non-universal power-law divergence of the correlation length in the critical domain and Berezinskii-Kosterlitz-Thouless divergence approaching it.

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Sondre Duna Lundemo, Flavio S. Nogueira, Asle Sudbø. 2024-12-11. Topology-driven deconfined quantum criticality in magnetic bilayers. https://doi.org/10.1103/physrevb.111.075158

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