Resistive Barkhausen noise at room temperature in thin ferromagnetic wires

We studied the magnetoresistance of Ni wires of micron-range diameter with diameter fluctuations prepared with a simple electrochemical method. The transverse magnetoresistance at room temperature showed abrupt jumps, which strongly depended on the angle of the magnetic field with respect to the wire. We consider that these jumps are resistive Barkhausen noise due to the motion of domain walls. The artificially introduced diameter fluctuations in the sample wires, associated with the fluctuations of coercivity along the sample, were essential for the Barkhausen noise to appear. The mechanisms of pinning a domain wall in our samples and a possible novel engineering application of the Barkhausen noise are discussed.