Dimensional crossover in a spin liquid to helimagnet quantum phase transition.

Abstract

Neutron scattering is used to study magnetic field induced ordering in the quasi-1D quantum spin-tube compound Sul-Cu2Cl4 that in zero field has a non-magnetic spin-liquid ground state. The experiments reveal an incommensurate chiral high-field phase stabilized by a geometric frustration of the magnetic interactions. The measured critical exponents beta= 0.235 and nu ~0.34 at Hc ~ 3.7 T point to an unusual sub-critical scaling regime and may reflect the chiral nature of the quantum critical point.