Synthesis, X-ray diffraction and Magnetic measurements of Cu (Ni, Co) In S4 alloys: Superconductor behavior of CuCo2InS4

Polycrystalline samples of CuCo2InS4 and CuNi2InS4 alloys were prepared by the melt and anneal method. The products were characterized by X-Ray Diffraction (XRD) and Superconducting Quantum Interference Device (SQUID) techniques. From XRD it was found that both alloys, CuCo2InS4 and CuNi2InS4, are composed by two orthorhombic phases. In the case of CuCo2InS4, the crystal structure of the main phase has been refining (Rietveld method) as Pmn21 (N 31) with lattice parameters a=8.100(1) A, b=7.116(8) A and c=6.391(6) A; for CuNi2InS4, the lattice parameters of the two phases were indexed (DICVOL 06). With respect to the magnetic behavior, CuCo2InS4 is a superconductor with Tc=3.2 K whereas CuNi2InS4 is a high temperature (Tc ~ 380 K) weak ferromagnetic with abnormal temperature dependence of the coercitive field.