Reduction of the Ordered Magnetic Moment by Quantum Fluctuation in the Antiferromagnetic Spin-\(\frac{5}{2}\) Dimer Compound FeVMoO7

We investigated the magnetism of FeVMoO7 by performing magnetization, specific heat, electron spin resonance, and neutron diffraction experiments. We observed an antiferromagnetically ordered state below T-N = 10.8 K. We consider that the probable spin model is an interacting antiferromagnetic spin-5/2 dimer model where spin dimers are connected by interdimer interactions. The intradimer interaction was evaluated to be J = 10.5 +/- 0.5 K. The magnitude of ordered magnetic moments is 4.00(7)mu(B) at 4K. The magnitude at 0 K is considered to be smaller than the classical value 4.95;mu(B )(g = 1.98). We confirmed a reduction of ordered magnetic moments by quantum fluctuation in high-spin (spin-5/2) clusters as known in high-spin chains.