Four odd-even spin phenomena are observed in electronic transport through a quantum wire. They consistently imply that a quasi-one-dimensional system tends to a spontaneous spin polarization with the energy band of minority spin-up electrons being reluctant to populate, thus widening the spin gap in energy. Variation of $g$ factor within a single subband is measured using a dc conductance technique, showing clear evidence of an oscillatory $g$ value as 1D subbands are filled one by one with increasing carrier density.

• Received 24 November 2008

DOI:https://doi.org/10.1103/PhysRevB.79.081301