Extremely high excitonic $g$-factors in 2D crystals by alloy-induced admixing of band states

Abstract

Monolayers (MLs) of semiconducting transition metal dichalcogenides (\mbox{S-TMDs}) emit light very efficiently and display rich spin-valley physics, with gyromagnetic ($g$-) factors of about -4. Here, we investigate how these properties can be tailored by alloying. Magneto-optical spectroscopy is used to reveal the peculiar properties of excitonic complexes in Mo${}_x$W${}_{1-x}$Se${}_2$ MLs with different Mo and W concentrations. We show that the alloys feature extremely high $g$-factors for neutral excitons, that change gradually with the composition up to reaching values of the order of -10 for $x\approx 0.2$. First-principles calculations corroborate the experimental findings and provide evidence that alloying in S-TMDs results in a non-trivial band structure engineering, being at the origin of the high $g$-factors. The theoretical framework also suggests a higher strain sensitivity of the alloys, making them promising candidates for tailor-made optoelectronic devices.

9 pages, 5 figures, SM

References in corpus (23)

• k.p theory for two-dimensional transition metal dichalcogenide semiconductors
• Probing the influence of dielectric environment on excitons in monolayer WSe2: Insight from high magnetic fields
• Brightening of dark excitons in monolayers of semiconducting transition metal dichalcogenides
• Optical imaging of strain in two-dimensional crystals
• Dark excitons in transition metal dichalcogenides
• Valley Phonons and Exciton Complexes in a Monolayer Semiconductor
• Variation of the fundamental band gap nature in curved two-dimensional WS2
• Emerging Photoluminescence from the Dark-Exciton Phonon Replica in Monolayer WSe2
• Optical response of monolayer, few-layer and bulk tungsten disulfide
• Gate tunable dark trions in monolayer WSe${}_2$
• Optical investigation of monolayer and bulk tungsten diselenide (WSe${}_2$) in high magnetic fields
• Excitonic valley effects in monolayer WS${}_2$ under high magnetic fields
• Momentum-Dark Intervalley Exciton in Monolayer Tungsten Diselenide Brightened via Chiral Phonon
• Multipath optical recombination of intervalley dark excitons and trions in monolayer WSe${}_2$
• Moiré-trapped interlayer trions in a charge-tunable WSe${}_2$/MoSe${}_2$ heterobilayer
• Excitonic complexes in $n$-doped WS${}_2$ monolayer
• Nonlinear optical selection rules of excitons in monolayer transition metal dichalcogenides
• Rydberg series of dark excitons and the conduction band spin-orbit splitting in monolayer WSe${}_2$
• Exposing the trion's fine structure by controlling the carrier concentration in hBN-encapsulated MoS${}_2$
• The effect of dielectric environment on the brightening of neutral and charged dark excitons in WSe${}_2$ monolayer
• Excitons and trions in WSSe monolayers
• Analogy and dissimilarity of excitons in monolayer and bilayer of MoSe${}_2$
• Proximity-enhanced valley Zeeman splitting at the WS${}_2$/graphene interface