Magnetic field effect on Fe-induced short-range magnetic correlation and electrical conductivity in Bi_1.75 Pb_0.35 Sr_1.90 Cu_0.91 Fe_0.09 O_6+y

We report electrical-resistivity measurements and neutron-diffraction studies under magnetic fields of Bi_1.75 Pb_0.35 Sr _1.90 Cu_0.91 Fe_0.09 O_6+y, in which hole carriers are overdoped. This compound shows short-range incommensurate magnetic correlation with incommensurability δ=0.21, whereas a Fe-free compound shows no magnetic correlation. Resistivity shows an up turn at low temperature in the form of ln (1/T) and shows no superconductivity. We observe reduction in resistivity by applying magnetic fields (i.e., a negative magnetoresistive effect) at temperatures below the onset of short-range magnetic correlation. Application of magnetic fields also suppresses the Fe-induced incommensurate magnetic correlation. We compare and contrast these observations with two different models: (1) stripe order and (2) dilute magnetic moments in a metallic alloy with associated Kondo behavior. The latter picture appears to be more relevant to the present results.