Magnetic Properties of the Novel Frustrated Lattice Magnet Likasite

Magnetic properties of Cu3(OH)5(NO3)·2H2O (likasite) are studied by measuring magnetic susceptibility, specific heat and high field magnetization up to 73 T. Weiss temperature is estimated to be −16 K, and the dominant magnetic interaction in likasite is found to be antiferromagnetic. The magnetic susceptibility has a round maximum at around 12 K, which is a characteristic of low-dimensional antiferromagnets. A long range magnetic order is not observed down to 2 K, suggesting the spin frustration effect. The high field magnetization measured at 1.3 K and 4.2 K appears to saturate above 40 T but the “saturation” value is only 2/3 of the expected saturation magnetization. This result is compared with the 2/3 magnetization plateau, theoretically suggested to stabilize in the diamond chain spin model by additional inter-monomer interactions.