Projects per year
Valleytronics is rapidly emerging as an exciting area of basic and applied research. In two-dimensional systems, valley polarization can dramatically modify physical properties through electron–electron interactions as demonstrated by such phenomena as the fractional quantum Hall effect and the metal-insulator transition. Here, we address the electrons’ spin alignment in a magnetic field in silicon-on-insulator quantum wells under valley polarization. In stark contrast to expectations from a non-interacting model, we show experimentally that less magnetic field can be required to fully spin polarize a valley-polarized system than a valley-degenerate one. Furthermore, we show that these observations are quantitatively described by parameter-free ab initio quantum Monte Carlo simulations. We interpret the results as a manifestation of the greater stability of the spin- and valley-degenerate system against ferromagnetic instability and Wigner crystalization, which in turn suggests the existence of a new strongly correlated electron liquid at low electron densities.
Renard, V. T., Piot, B. A., Waintal, X., Fleury, G., Cooper, D., Niida, Y., Tregurtha, D., Fujiwara, A., Hirayama, Y., & Takashina, K. (2015). Valley polarization assisted spin polarization in two dimensions. Nature Communications, 6, 1-8. . https://doi.org/10.1038/ncomms8230