Magnetocaloric Effect and Magnetoresistance Due to Itinerant Electron Metamagnetic Transition in ${rm Co}({rm S}_{1-x}{rm Se}_{x})_{2}$

摘要

The ${rm Co}({rm S}_{1-x}{rm Se}_{x})_{2}$ compounds with the cubic Pyrite structure show itinerant electron metamagnetism for $0.12leq x$ . We studied the magnetocaloric effect and magnetoresistance (MR) of this system. It was found that a substantial magnetic entropy change was obtained for ${rm Co}({rm S}_{0.88}{rm Se}_{0.12})_{2}$ , which has a paramagnetic ground state. We observed giant positive MR associated with the itinerant electron metamagnetic transition for ${rm Co}({rm S}_{1-x}{rm Se}_{x})_{2}$ . The magnitude of the MR jump is independent of temperature and concentration for $0.13leq xleq 0.15$ . These results are discussed in terms of a simple band structure of ${rm CoS}_{2}$ , in which high-spin polarization is realized in a ferromagnetic state.