We report high-field magnetization and magnetostriction measurements on the rare-earth-metal tetraboride ${\mathrm{TbB}}_4$, in which the Tb moments form a Shastry-Sutherland lattice in the tetragonal basal plane. A number of magnetization plateaus appear when the magnetic field is perpendicular to the magnetic easy plane. We propose that the magnetization plateaus arise from the combined effect of magnetic frustration and quadrupole interaction in the unique two-dimensional network.

• Received 4 September 2007

DOI:https://doi.org/10.1103/PhysRevLett.101.087202