Using symmetry breaking strain to tune the valley occupation of a two-dimensional (2D) electron system in an AlAs quantum well, together with an applied in-plane magnetic field to tune the spin polarization, we independently control the system's valley and spin degrees of freedom and map out a spin-valley phase diagram for the 2D metal-insulator transition. The insulating phase occurs in the quadrant where the system is both spin- and valley-polarized. This observation establishes the equivalent roles of spin and valley degrees of freedom in the 2D metal-insulator transition.
@article{arxiv.cond-mat/0609493,
title = {Spin-valley phase diagram of the two-dimensional metal-insulator transition},
author = {O. Gunawan and T. Gokmen and K. Vakili and M. Padmanabhan and E. P. De Poortere and M. Shayegan},
journal= {arXiv preprint arXiv:cond-mat/0609493},
year = {2014}
}