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arXiv · 2608.27411

A continuous confinement-deconfinement transition in a triangular quantum magnet

Suguru Hosoi·Sejun Park·Michihiro Hirata·Minseong Lee·Adam P Dioguardi·Joe D Thompson·Filip Ronning·Allen O Scheie·Kumpei Imamura·Kenichiro Hashimoto·Takasada Shibauchi·Bishnu P Belbase·Arjun Unnikrishnan·Johannes Knolle·Arnab Banerjee·Yuji Matsuda
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Abstract

A continuous transition between phases hosting distinct excitations---bosonic magnons versus fermionic spinons---is a long-sought phenomenon in quantum magnetism, analogous to the confinement--deconfinement transition in quantum chromodynamics. We report evidence for such a transition in the triangular-lattice antiferromagnet TlYbS$_2$. Antiferromagnetic order develops below $T_\mathrm{N} \approx 0.53\,\mathrm{K}$. A $c$-axis field suppresses this order, driving the system into a gapless quantum spin liquid with a spinon Fermi surface above $\mu_0 H_\mathrm{c} \approx 3\,\mathrm{T}$, evidenced by a finite residual linear term in thermal conductivity, a Pauli-like susceptibility, and a temperature-independent NMR Knight shift. Approaching $H_\mathrm{c}$ from above, the scattering rate of itinerant excitations is strongly enhanced while their density of states shows no critical enhancement, atypical of conventional magnetic quantum criticality. These results point to a continuous confinement--deconfinement transition governed by fractionalized excitations beyond the Ginzburg--Landau paradigm.

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Suguru Hosoi, Sejun Park, Michihiro Hirata, Minseong Lee, Adam P Dioguardi, Joe D Thompson, Filip Ronning, Allen O Scheie, Kumpei Imamura, Kenichiro Hashimoto, Takasada Shibauchi, Bishnu P Belbase, Arjun Unnikrishnan, Johannes Knolle, Arnab Banerjee, Yuji Matsuda. 2026-08-27. A continuous confinement-deconfinement transition in a triangular quantum magnet. https://arxiv.org/abs/2608.27411

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