Fig. 1. (a) Optical topography of the CVD-grown large-scale WSe2 monolayer on SiO2/Si surface, where the tweezer trace shows the distinction between WSe2 film and the substrate. (b), (c) HRTEM image and SAED pattern of monolayer H/T-WSe2. (d) XPS of monolayer H/T-WSe2. The blue and purple shadows correspond to the components of H and T phases, respectively. (e) I–V curves of monolayer H-WSe2 and H/T-WSe2 with the T-phase components of 12.2% and 19.9%. (f) Atomic structure of monolayer H/T-WSe2, and the differential charge densities of top Se, W, and bottom Se atomic layers. The scale bar from blue to red denotes the change from depletion to accumulation.

Fig. 2. Circularly polarized PL spectra of H/T-WSe2-19.9% under (a)–(d) positive magnetic fields from 1 to 4 T and (e)–(h) negative magnetic field from −1 to −4 T. The blue and purple lines indicate co- and cross-polarized configurations, respectively.

Fig. 3. Magnetic-dependent polarization of (a) H/T-WSe2-12.2% and (b) H/T-WSe2-19.9% under σ− excitation with σ− and σ+ detection. The red dots indicate the measurement data. The dark blue, light blue, and pink lines show slopes from 0 to ±1T, ±1 to ±2T, and ±2 to ±4T, respectively. Spin density isosurface plots of (c) H-WSe2 and (d) H/T-WSe2. The W and Se atoms are denoted by the blue and yellow balls, respectively. The isosurface in pink represents the majority spin density. Total spin DOSs of monolayers (e) H-WSe2 and (f) H/T-WSe2, where the pink and blue lines denote the majority and minority spin DOS.

Fig. 4. Schematic diagram of magnetic-field-modulated valley dynamic process of monolayer H-WSe2 and H/T-WSe2. (a) SOC-induced valence band splitting in H-WSe2. (b) SOC induced band splitting in H/T-WSe2 with the electron concentration increases due to the introduction of T phase in H-WSe2. (c) Magnetic-field-induced exciton dispersion in conduction band and valley splitting in valence band of H/T-WSe2. (d) Cartoons depicting valley polarization in H/T-WSe2 under the (d) positive and (e) negative magnetic fields, respectively. The thick arrows with single color (γ1) denote the asymmetric valley-conserving and the thin arrows (γ2) with color gradient denote the valley-flipping exciton formation processes under σ+ and σ− excitation.