| Transition metal Chalcogenides exhibit a great variety of complex physical responses or properties, most of which are still not fully understood. This work will present a few interesting examples that are suggestive of phase competition in various circumstances. The pyrite (Co, Fe)(S, Se)2 system exhibits competition between itinerant antiferromagnetic (AF) and ferromagnetic (FM) metallic phases, resulting in unusual metamagnetism. The Cu(Ir, Cr) 2S4 system has been found to have a very interesting phase diagram, exhibiting simultaneous charge-ordering and spin dimerization before undergoing an insulator-metal transition to a ferromagnetic state. Finally, we have observed superconductivity in CuRh2Se4, which is remarkably sensitive to very minute (∼0.5%) traces of Cr-doping, before ferromagnetism sets in at the magnetic percolation threshold. |
