Coexistence of Superconductivity and Ferromagnetism in Ni-Doped Bi_(4−x)Ni_xO_4S_3 (0.075 ≤ x ≤ 0.150)

Abstract

The effects of Ni doping on the physical properties of the newly discovered layered superconductor Bi_4O_4S_3 are studied. X-ray diffraction data indicates that the lattice constants a and c decrease with the increasing Ni doping. From resistivity-temperature curves, the superconducting transition temperature (T_c^(onset) is suppressed by only 0.5 K with the increase of Ni doping from 0.075 to 0.15; the T_c^(zero) is almost the same constant at different Ni ions' doping level. The magnetic susceptibility results suggest the coexistence of superconductivity and ferromagnetism in this system. A possible superconductivity transition is observed around ˜14 K from M-T (FC) curves in x = 0.125, 0.15 samples, which may result from the doped magnetic Ni ions.

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