2019/11/30 by Rahul Debnath, Debnath, Rahul, Indrajit Maity +5 · 4 citations
Physics and Astronomy · Materials Science · #Quantum and electron transport phenomena #Mechanical and Optical Resonators #2D Materials and Applications
paper · pdf · doi:10.48550/arxiv.1912.00139
Twisted van der Waals heterostructures unravel a new platform to study\nstrongly correlated quantum phases. The interlayer coupling in these\nheterostructures is sensitive to twist angles (\θ) and key to\ncontrollably tune several exotic properties. Here, we demonstrate a systematic\nevolution of the interlayer coupling strength with twist angle in bilayer\n mathrmMoS2 using a combination of Raman spectroscopy and classical\nsimulations. At zero doping, we show a \monotonic increment of the\nseparation between the mathrmA1g and mathrmE12g mode\nfrequencies as \θ decreases from 10\∘ \→ 1\∘, which\nsaturates to that for a bilayer at small twist angles. Furthermore, using\ndoping-dependent Raman spectroscopy we reveal \θ dependent softening and\nbroadening of the mathrmA1g mode, whereas the mathrmE12g\nmode remains unaffected. Using first principles-based simulations we\ndemonstrate large (weak) electron-phonon coupling for the mathrmA1g\n( mathrmE12g) mode explaining the experimentally observed trends. Our\nstudy provides a non-destructive way to characterize the twist angle, the\ninterlayer coupling and establishes the manipulation of phonons in twisted\nbilayer mathrmMoS2 (twistnonics).\n