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Spin-orbit engineering in transition metal dichalcogenide alloy monolayers.

Gang WangCedric RobertAslihan SusluBin ChenSijie YangSarah AlamdariIann C GerberThierry AmandXavier MarieSefaattin TongayBernhard Urbaszek
Published in: Nature communications (2015)
Binary transition metal dichalcogenide monolayers share common properties such as a direct optical bandgap, spin-orbit splittings of hundreds of meV, light-matter interaction dominated by robust excitons and coupled spin-valley states. Here we demonstrate spin-orbit-engineering in Mo(1-x)WxSe2 alloy monolayers for optoelectronics and applications based on spin- and valley-control. We probe the impact of the tuning of the conduction band spin-orbit spin-splitting on the bright versus dark exciton population. For MoSe2 monolayers, the photoluminescence intensity decreases as a function of temperature by an order of magnitude (4-300 K), whereas for WSe2 we measure surprisingly an order of magnitude increase. The ternary material shows a trend between these two extreme behaviours. We also show a non-linear increase of the valley polarization as a function of tungsten concentration, where 40% tungsten incorporation is sufficient to achieve valley polarization as high as in binary WSe2.
Keyphrases
  • transition metal
  • room temperature
  • density functional theory
  • single molecule
  • mass spectrometry
  • molecular dynamics
  • fluorescent probe