Аннотация
External fields are a powerful tool to probe optical excitations in a
material. The linear energy shift of an excitation in a magnetic field
is quantified by its effective g factor. Here we show how exciton g
factors and their sign can be determined by converged first-principles
calculations. We apply the method to monolayer excitons in
semiconducting transition metal dichalcogenides and to interlayer
excitons in MoSe2/WSe2 heterobilayers and obtain good agreement with
recent experimental data. The precision of our method allows us to
assign measured g factors of optical peaks to specific transitions in
the band structure and also to specific regions of the samples. This
revealed the nature of various, previously measured interlayer exciton
peaks. We further show that, due to specific optical selection rules, g
factors in van der Waals heterostructures are strongly spin and
stacking-dependent. The calculation of orbital angular momenta requires
the summation over hundreds of bands, indicating that for the considered
two-dimensional materials the basis set size is a critical numerical
issue. The presented approach can potentially be applied to a wide
variety of semiconductors.
Пользователи данного ресурса
Пожалуйста,
войдите в систему, чтобы принять участие в дискуссии (добавить собственные рецензию, или комментарий)