Effect of spin fluctuations on the thermodynamic and transport properties of the itinerant ferromagnet COS2

Through a detailed study of the specific heat, resistivity, and susceptibility under pressure in polycrystalline and single-crystal CoS 2, we demonstrate that the thermodynamic and transport properties of this system are governed by spin-density fluctuations. We give the correct (P,T) coordinates of its tricritical point and discuss the origin of the first-order magnetic phase transition in this system. Our results highlight the importance of having clean single crystals in order to extract definitive conclusions about the intrinsic properties of itinerant weak ferromagnets. © 2008 The American Physical Society.