  Using an elastic neutron scattering technique under a pulsed magnetic field
up to 30 T, we determined the magnetic structure in the half-magnetization
plateau phase in the spinel CdCr$_2$O$_4$. The magnetic structure has a cubic
$P4_3$32 symmetry, which is the same as that observed in HgCr$_2$O$_4$. This
suggests that there is a universal field induced spin-lattice coupling
mechanism at work in the Cr-based spinels.
