title: Exciton diamagnetic shifts and valley Zeeman effects in monolayer WS2 and MoS2 to 65 Tesla.
abstract: In bulk and quantum-confined semiconductors, magneto-optical studies have historically played an essential role in determining the fundamental parameters of excitons (size, binding energy, spin, dimensionality and so on). Here we report low-temperature polarized reflection spectroscopy of atomically thin WS2 and MoS2 in high magnetic fields to 65 T. Both the A and B excitons exhibit similar Zeeman splittings of approximately -230 μeV T(-1) (g-factor ≃-4), thereby quantifying the valley Zeeman effect in monolayer transition-metal disulphides. Crucially, these large fields also allow observation of the small quadratic diamagnetic shifts of both A and B excitons in monolayer WS2, from which radii of ∼1.53 and ∼1.16 nm are calculated. Further, when analysed within a model of non-local dielectric screening, these diamagnetic shifts also constrain estimates of the A and B exciton binding energies (410 and 470 meV, respectively, using a reduced A exciton mass of 0.16 times the free electron mass). These results highlight the utility of high magnetic fields for understanding new two-dimensional materials.
authors: National High Magnetic Field Laboratory, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA.
authors: Andreas V
authors: AV
authors: Stier
authors: Materials Science and Technology Division, Naval Research Laboratory, Washington, Washington DC 20375, USA.
authors: Kathleen M
authors: KM
authors: McCreary
authors: Materials Science and Technology Division, Naval Research Laboratory, Washington, Washington DC 20375, USA.
authors: Berend T
authors: BT
authors: Jonker
authors: Department of Electrical and Computer Engineering, Rice University, Houston, Texas 77005, USA.|Department of Physics and Astronomy, Rice University, Houston, Texas 77005, USA.|Department of Materials Science and NanoEngineering, Rice University, Houston, Texas 77005, USA.
authors: Junichiro
authors: J
authors: Kono
authors: National High Magnetic Field Laboratory, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA.
authors: Scott A
authors: SA
authors: Crooker