Effect of 3d Metal (Co and Ni) Doping on the Superconductivity of FeSe0.5Te0.5

摘要

We report the effect of 3d metal Cobalt (Co) and Nickel (Ni) doping on theFeTe0.5Se0.5 superconductor with the nominal composition rangeFe1-xMxTe0.5Se0.5 (M = Co, Ni and x = 0.00, 0.01 0.02, 0.05, and 0.10). Samplesare synthesized through standard solid state reaction route and all arecrystallize in single phase tetragonal structure with space group P4nmm. Thelattice parameters 'a', 'c' and volume decrease with increase in Co and Nicontent, although not monotonically. In fact the 'a' lattice parameter of Codoped samples is nearly unaffected for Co doped samples. The superconductingtransition temperature (Tc) is measured from both DC and AC magneticsusceptibility, which decrease with increase in Ni or Co content. Both Co andNi suppress Tc and drive the system into the normal state. Interestingly, Nisuppresses the superconductivity much faster than the Co. This indicates lesseffect on in-plane Fe-Se distances and thus reduced disorder in case of Co whencompared with Ni substation at Fe site in FeTe0.5Se0.5 superconductor. It isconcluded that in-plane disorder on superconducting Fe-Se and Fe-Se-Se planesdirectly affects superconductivity in FeTe0.5Se0.5 superconductor.