The induced electrorheological solid has thick columns in the field direction (z axis), spreading between two electrodes. The ground state is proposed to be a body-centered tetragonal lattice with ${\mathbf{a}}_1$= √6 ax^, ${\mathbf{a}}_2$= √6 ay^, and ${\mathbf{a}}_3$=2az^, where a is the radius of dielectric spheres. This bct lattice can be regarded as a compound of chains of class A and B, where chains B are obtained from chains A by shifting a distance a in the z direction.

• Received 19 February 1991

DOI:https://doi.org/10.1103/PhysRevLett.67.398