Extended Data Fig. 3: Pump–probe spectroscopy of tMoTe₂ device D3 with a twist angle θ = 5.5°.

a, Optical image (approximately 100 µm × 100 µm) of device D3. b, PL spectra as a function doping level (estimated from calculated capacitance). The left and right panels show displacements fields of D = 0 and −0.02 V nm⁻¹; the latter is used to compensate for a small build-in potential. c–e, Transient reflection spectrum as a function of total gate voltage V_g (V) and probe photon energy E (ħω₂) at pump–probe delays of Δt = 7 ps (c), Δt = 13 ps (d) and Δt = 500 ps (e). The pump (0.99 eV) and probe fluences are at 42 µJ cm⁻² and 22 µJ cm⁻², respectively. Sample temperature T = 1.6 K. There is no external magnetic field (B = 0) or displacement field (D = 0). The gate voltage ranges in c–e correspond to the same estimated doping range shown in the PL maps in b. No specific states (at particular V_g or doping levels) are resolved in the pump–probe spectral maps at all three selected Δt values (7, 13 and 500 ps), in agreement with the PL maps in b. The transient spectral maps feature exciton and trion resonances, with energy splitting in certain doping ranges; these splitting features have been observed before and are attributed to exciton/trion fine structures in MoTe₂ monolayers^44,45 and/or exciton polarons in tMoTe₂ bilayers⁴⁶. The broad contrasts in exciton/trion ΔR/R signal vary slowly with Δt and probably result from the dynamics or hot-carrier relaxation, carrier-phonon scattering, phonon cooling and balances in exciton and trion populations.