  CuCrS2, a Heisenberg antiferromagnet with layered edge sharing triangular
lattice, exhibits a spiral magnetic order. Dielectric (E) and polarization
studies show magnetoelectric (ME) coupling at Neel temperature (T_N=38 K) where
simultaneous dielectric and magnetic long range order occur. The compound shows
a diffused ferroelectric (FE) transition and slow relaxation dynamics above
T_N, indicative of relaxor FE behavior. Interestingly, memory effect and
magnetic field induced rejuvenation are also observed in E, establishing
cooperative glassy dynamics and ME coupling even above T_N. We discuss the role
of geometrical frustration and metal ligand hybridization for these unusual
properties.
