| Low dimensional quantum spin systems provide a rich variety of exotic phenomena such as spin liquids and fractional excitations. Considerable quantum fluctuations prevent order down to lowest temperatures and lead to a macroscopic ground state degeneracy. The coupled spin chain system (NO)[Cu(NO3)3] is proposed to be a realization of the confederate flag model with a spin liquid ground state and deconfined spinon excitations. Our Raman scattering study reveals a broad magnetic scattering continuum that is suppressed at low temperatures, pointing to the opening of a gap for singlet excitation. From magnetic susceptibility no spin gap is obvious. Additionally, Raman scattering reveal phonon anomalies that point to a symmetry reduction in the low temperature phase. Work supported by DFG, NTH and B-IGSM. |
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