Magnetic phase diagram of the frustrated quantum ferro-antiferromagnet Cs₂Cu₂Mo₃O₁₂

A single-crystal sample of the frustrated quantum magnet Cs₂Cu₂Mo₃O₁₂ is investigated by means of magnetic and thermodynamic measurements. A combination of specific heat and magnetic torque measurements maps out the entire H-T phase diagram for three magnetic field orientations. Remarkably, a new phase emerges below the saturation field, irrespective of the crystal orientation. It is suggested that the presaturation phase represents spin-nematic order or other multimagnon condensate. The phase diagrams within the long-range ordered dome are qualitatively different for each geometry. In particular, multiple transitions are identified at low temperature in a field along the (010) direction.

Reference: D. Flavián et al., Phys. Rev. B 101, 224408 (2020).