Oscillating magnetoresistance of (Bi,Pb)2Sr2Ca2Cu3O x ceramics doped with Mn

The magnetoresistance nearT _c(T _cR=0=100 K) has been measured on ceramic samples of (Bi, Pb)₂Sr₂Ca₂(Cu_0.98Mn_0.02)₃O_x (X-Ray diffractions and measurements by a SQUID magnetometer give almost single 2223 phase) in magnetic fields, up to 60 kOe using a dc four-probe technique. We observed periodic oscillations superimposed on a monotonie growth of the magnetoresistance with the amplitude decreasing with increase in magnetic field. Fourier transforms of the magnetoresistance data gives two sharply pronounced periods, 10.7 and 14.7 kOe. Apparently these oscillations are connected with inhomogeneous distributions of Mn in superconducting grains with phase slippage at grain boundaries.