Is the valley the points K and K’ of the Brillouin zone?
What people call the valley are inequivalent points of the Brillouin zone? In MoS2 the are two inequivalent points, the K and the K', that are related by the temporal inversion symmetry, and the spin-orbit coupling at this points is opposite. Are this two points each one a valley?
Or is it the conduction band minimum that is called the valley?