Magnetism of the antiferromagnetic spin-$frac{3}{2}$ dimer compound CrVMoO$_7$ having an antiferromagnetically ordered state

We measured magnetization, specific heat, electron spin resonance, neutron diffraction, and inelastic neutron scattering of CrVMoO$_7$ powder. An antiferromagnetically ordered state appears below $T_{rm N} = 26.5 pm 0.8$ K. We consider that the probable spin model for CrVMoO$_7$ is an interacting antiferromagnetic spin-$frac{3}{2}$ dimer model. We evaluated the intradimer interaction $J$ to be $25 pm 1$ K and the effective interdimer interaction $J_{rm eff}$ to be $8.8 pm 1$ K. CrVMoO$_7$ is a rare spin dimer compound that shows an antiferromagnetically ordered state at atmospheric pressure and zero magnetic field. The magnitude of ordered moments is $0.73(2) mu_{rm B}$. It is much smaller than a classical value $sim 3 mu_{rm B}$. Longitudinal-mode magnetic excitations may be observable in single crystalline CrVMoO$_7$.