Novel phenomenon of magnetism and superconductivity in Fe-doped superconductor Bi_(4−x) Fe_x O_4S_3 (0 ≤ x ≤ 0.1)

Abstract

We report the effects of Fe doping on the BiS_2-based superconductor Bi_4O_4S_3. It has been found that the superconducting transition temperature (T^(onset)_C) is slightly enhanced by Fe doping. The magnetic susceptibility results reveal the coexistence of superconductivity and long-range ferrimagnetism in these samples. A new magnetic transition temperature TV (Verwey transition) from the M–T curves at ~112 K is observed. The isothermal magnetization curves (M–H) indicate a weak ferrimagnetism, which is probably due to the antiparallel ordering of Fe^(2+) and Fe^(3+) magnetic moments. The coexistence of superconductivity and ferro/ferrimagnetism makes bismuth oxysulfide superconductor a platform for understanding superconductivity from a new perspective.

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