Magnetoelectric Effect and Spin Direction in a Spin Flopped Cr2O3Single Crystal

Magnetoelectric susceptibilities α 33 and α 23 of an antiferromagnetic Cr 2 O 3 single crystal have been measured in a pulsed magnetic field up to about 100 kOe. Here the 1-, 2- and 3-axes are along the binary axis, in the glide plane and along the trigonal axis, respectively. Both α 33 and α 23 have a finite value after a spin flop transition in the range from liquid helium temperature to room temperature. This result leads to the conclusion that the magnetic point symmetry of spin flopped Cr 2 O 3 is 2/ m ' or 1'. The compatible spin direction in the basal plane must have a component normal to the binary axis.