High-pressure synthesis and magnetic properties of orthorhombic CuRh2O4

Polycrystals of orthorhombic CuRh2O4 were prepared by a solid state reaction under high pressure and its magnetic properties were compared with those of polymorph-tetragonal CuRh2O4 (spinet-type compound). The orthorhombic phase undergoes antiferromagnetic transition at 24 K. The ratio of the Curie-Weiss temperature (theta(CW)) to the Met temperature (T-N) is estimated to be f = vertical bar theta(CW)vertical bar/T-N = 2.6 and is considerably smaller than f in the tetragonal phase, 5.3. This indicates that geometrical magnetic frustration inherent in the Cu2+ network of the spinet structure is released in the orthorhombic phase with lower crystal symmetry. We observed a weak ferromagnetism below TN in the orthorhombic phase; this is also discussed in terms of crystal symmetry.