  Quantum transport and spintronics regimes are studied in p- and n-doped
atomic layers of hexagonal transition metal dichalcogenides (TMDCs), subject to
the interplay between the valley structure and spin-orbit coupling. We find how
spin relaxation of carriers depends on their areal density and show that it
vanishes for holes near the band edge, leading to the density-independent spin
diffusion length, and we develop a theory of weak
localisation/antilocalisation, describing the crossovers between the
orthogonal, double-unitary and symplectic regimes of quantum transport in
TMDCs.
