Antiferromagnetic ordering of S=1/2 triangles in La4Cu3MoO12

Magnetic properties of a cupric triangular cluster compound La4Cu3MoO12 were investigated. Susceptibility data show that paramagnetic cupric spin (S=1/2) above room temperature forms S=1/2 trimers at lower temperatures because of strong intratrimer antiferromagnetic interactions. The cluster moments acquire antiferromagnetic order below 2.6 K. The trimers can be polarized in an external field of 20 T at 1.3 K. The magnetization remains nearly constant at 1 mu(B) per trimer up to a magnetization plateau at 55 T.