Electric-field control of magnetization in biased semiconductor quantum wires and point contacts

The true origin of the 0.25 and 0.85 conductance features which have been observed in biased split-gate quantum wires and quantum point contacts in semiconductor heterostructures is debated in the literature; one suggestion is that they are caused by spontaneous spin polarization due to the electron-electron interactions. The present work confirms that spontaneous spin splitting may occur within the system and is responsible for both the 0.25 and 0.85 plateaux. We have also shown that the 0.25 plateau consists of two regions, one that is spin polarized, and one that is degenerate with a conductance that remains essentially the same at both sides of the transition. This finding could be of interest for semiconductor spintronics because it opens the possibility for spin manipulation by electric means only.