Two-Step Magnetic Ordering in Quasi-One-Dimensional Helimagnets: Possible Experimental Validation of Villain's Conjecture about a Chiral Spin Liquid Phase

Low-temperature specific heat, magnetic susceptibility, and zero-field muon spin resonance (muSR) measurements have been performed in the quasi-one-dimensional molecular helimagnetic compound Gd(hfac)3NITEt. The specific heat presents two anomalies at T0=2.19±0.02 K and TN=1.88±0.02 K, which both disappear upon the application of a weak magnetic field. Conversely, magnetic susceptibility and muSR data show the divergence of two-spin correlation functions only at TN=1.88±0.02 K. These results suggest an experimental validation of Villain's conjecture of a two-step magnetic ordering in quasi-one-dimensional XY helimagnets; i.e., the paramagnetic phase and the helical spin solid phase are separated by a chiral spin liquid phase, where translational invariance is broken without violation of rotational invariance.