Quantized [e.sup.2]/h step and nonquantized step in nanocontact magnetoresistance

Electron transport property in the nanocontacting wire was investigated by measuring magnetoresistance effect. In the regime of conductance quantization, the magnetoresistance exhibits the quantized step (in the unit of [e.sup.2]/h) and nonquantized step ([DELTA]G < [e.sup.2]/h). The magnetoresistance effect appears to be large in the case that either of the steps was observed in a magnetoresistance curve, indicating that there are different mechanisms which bring about the giant magnetoresistance. Index Terms--Ballistic magnetoresistance (BMR), conductance quantization, nanocontact.