Engineering of excitonic g-factors in van der Waals structures

We develop a fully ab-initio based method of calculation of excitonic g-factors, which describe their energy dependence on external magnetic field, and apply it to 1L TMDs and MoSe2/WSe2 heterobilayers, obtaining excellent agreement with experimental data for intra- and interlayer excitons. A proper inclusion of stacking-dependent selection rules allows to assign the measured optical peaks to specific transitions in the band structure and regions of the samples [1]. We identify a series of magneto-PL peaks in 1L WS2 based on the calculated g-factors of excitons, trions and biexcitons, as well as four phonon replicas of the dark trion. We obtain a perfect agreement of the individual bands g-factors with the values derived from experimental data [2]. We explain the reduction of a g-factor measured in MoSe2/WS2 by the spatial confinement of the mixed exciton in the moiré potential [3].
[1] PRB 105, 235408
[2] NanoLett 21, 2519
[3] arX:2204.01813