  We have studied the magnetic torque in uranium monosulfide (US) single
crystals to explore the magnetic anisotropy in this material. Uranium
monosulfide crystallizes in cubic, NaCl-type of crystal structure and exhibits
the largest magneto-crystalline anisotropy observed in cubic systems. By
performing detailed torque measurements we observe a strongly anisotropic
behavior in the paramagnetic phase due to crystal defects and quadrupolar pair
interactions. Our studies also confirm the presence of a large anisotropy in
the ferromagnetic state of the US system with the <100>, <111>, and <110>
directions being hard, easy, and intermediate axis, respectively. Furthermore,
the anisotropy in the paramagnetic phase shows similar characteristics to the
anisotropy observed in the ferromagnetic phase, as characterized by second and
fourth rank susceptibility terms. The similarity of the anisotropic behaviors
in paramagnetic and ferromagnetic phases is the consequence of strong
magneto-elastic properties in this system, which possibly lead to the
rhombohedral structural distortion, not only in the ferromagnetic phase but
also in the paramagnetic phase (induced by applied magnetic fiield).
