Antiferromagnetic ordering of S=1/2 triangles in La4Cu3MoO12

Magnetic properties of a cupric triangular cluster compound ${\mathrm{La}}_{4}{\mathrm{Cu}}_{3}{\mathrm{MoO}}_{12}$ were investigated. Susceptibility data show that paramagnetic cupric spin $(S=\frac{1}{2})$ above room temperature forms $S=\frac{1}{2}$ 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${\ensuremath{\mu}}_{\mathrm{B}}$ per trimer up to a magnetization plateau at 55 T.