Magnetic properties of the frustrated diamond chain compound Cu3(CO3)2(OH)2

Cu3(CO3)2(OH)2 (azurite), in which Cu2+ (S=1/2) monomers and dimers are arranged alternately along the b-axis to make an infinite chain, is regarded as an actual material for the frustrated diamond chain model. we have measured magnetic susceptibility, high field magnetization and 1H NMR of a natural mineral single crystal of azurite to investigate the magnetic properties. The experimental results were compared with the theoretical expectation to suggest the ground state of Cu3(CO3)2(OH)2 is in a gapless phase