Low-Temperature Heat Capacity
of a Kagome Lattice Compound

Novel magnetic behaviors arisen by the spin frustration effects in a triangular, Kagome lattices are attracting wide interests. We have performed a heat capacity measurements for the Kagome lattice compound of Cu3V2O7(OH)2·2H2O which is called as Volborthite. In order to attain absolute precision of the measurement, we have made a thin pellet from fine powder and adhered them on the flat sample stage of the relaxation calorimeter. The single exponential relaxation curvature was confirmed throughout the tameperature range between 0.8 K and 12 K. The magnetic heat capacity due to the frustration of Cu2+ ions arranged in the Kagome lattices has been observed as large heat capacity values remains at low temperatures and linearly temperature dependent contribution. In addition to this, curious kink like structure has been observed around 1 K, which may imply the existence of short-range type ordering in the lattice.

(by Yamashita & Y. Nakazawa)

	Fig. 1. Structure of the two–dimensional Kagome lattice.
	Fig. 2. Low–temperature heat capacity of Cu3V2O7(OH)2·2H2O and Zn substituted compound. The large heat capacity due to S=1/2 spins at low temperatures is observable.
	Fig. 3. The CpT −1 vs T plot of the Cu2+ compound around 1 K. The kink structure indicative of a formation of short–range structure is observed.