Quantum criticality and spin liquid phase in the Shastry-Sutherland model

Abstract

The two-dimensional quantum spin model proposed by Shastry and Sutherland more than four decades ago is notable for its realization in SrCu${}_{2}$(BO${}_{3}$)${}_{2}$. Here, the authors present numerical evidence of a gapless spin liquid phase in the model and discuss its connection to a deconfined quantum critical point. The new phase exists in a parameter regime where recent high-pressure heat capacity measurements on SrCu${}_{2}$(BO${}_{3}$)${}_{2}$ did not detect any low-temperature order, in contrast to the antiferromagnetic and plaquette-singlet phases existing at higher and lower pressures, respectively. Thus, the elusive spin liquid may exist in SrCu${}_{2}$(BO${}_{3}$)${}_{2}$.

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