Magnetic State of the Geometrically Frustrated Quasi-One-Dimensional Spin System Cu3Mo2O9 Studied by Thermal Conductivity

Abstract

We have measured the thermal conductivity of the geometrically frustrated quasi-one-dimensional spin system Cu3Mo2O9 in magnetic fields. A contribution of the thermal conductivity due to spins has been observed in the thermal conductivity along the spin chains. The thermal conductivity due to phonons, \(\kappa _{\text{phonon}}\), has been found to decrease by the application of a magnetic field, which has been explained as being due to the reduction in the spin gap originating from the spin-singlet dimers. Moreover, it has been found that \(\kappa _{\text{phonon}}\) increases with increasing field in high fields above ∼7 T at low temperatures. This suggests the existence of a novel field-induced spin state and is discussed in terms of the possible spin-chirality ordering in a frustrated Mott insulator.