The relation between nanocontact magnetoresistance and conductance quantized states

The reduction of size in magnetic materials gives rise to new effects with great potential for spin-based applications. For example, the giant magnetoresistance (GMR) effect observed in nanometer-sized ferromagnetic contacts (nanocontact MR) is thought to be promising for future magnetoresistive sensors; the nanocontact MR is far larger than the normal GMR. Theoretically, it was predicted that the giant MR in nanocontact is the scattering of ballistic electrons. It is then an important issue to clarify the origin of the MR experimentally. In this work, we present detailed nanocontact MR in the conductance-quantization regime where the electron transport is definitely ballistic.