Nanocontact magnetoresistance and quantized conductance

The behavior of the magnetoresistance (MR) effect in a ferromagnetic Ni nanocontact is investigated in the regime of conductance quantization (1/12900 Ω^-1). The giant MR effect is observed in the case that the nanocontact with quantized conductance is fabricated. We sometimes observe that the conductance discretely changes by the quantization unit of e²/h and that the quantized conductance is switched by the application of magnetic field. There exists a close relationship between nanocontact MR and quantized conductance.