Dimensional crossover in a spin liquid to helimagnet quantum phase transition

Neutron scattering is used to study magnetic field induced ordering in the quasi one dimensional quantum spin tube compound Sul Cu2Cl4 that in zero field has a nonmagnetic 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 0.235 and 0.34 at Hc 3.7 T point to an unusual subcritical scaling regime and may reflect the chiral nature of the quantum critical point