Possible observation of quantum spin-nematic phase in a frustrated magnet

Abstract

Significance Spin-nematic state in frustrated ferromagnet is one of the exotic states of matter at high magnetic field that could arise as the Bose–Einstein condensation of the two-magnon bound state. Its experimental detection in a real material has long been hindered by the fact that the order parameter of the spin-nematic state, spin quadrupole moment, is hard to detect with conventional magnetic probes available in high magnetic field. Here we design a calorimeter for the pulsed magnetic field studies and perform state-of-the-art measurements of heat capacity and magnetocaloric effect up to 33 T. These results provide strong prima facie evidence for a spin-nematic state in the copper-based mineral volborthite.