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 (mu SR) measurements have been performed in the quasi-one-dimensional molecular helimagnetic compound Gd(hfac)(3)NITEt. The specific heat presents two anomalies at T(0)=2.19 +/- 0.02 K and T(N)=1.88 +/- 0.02 K, which both disappear upon the application of a weak magnetic field. Conversely, magnetic susceptibility and mu SR data show the divergence of two-spin correlation functions only at T(N)=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.