Unlike conventional plasmonic media, polaritonic van der Waals (vdW) materials hold promise for active control of light–matter interactions. The dispersion relations of elementary excitations such as phonons and plasmons can be tuned in layered vdW systems via stacking using functional substrates. In this work, infrared nanoimaging and nanospectroscopy of hyperbolic phonon polaritons are demonstrated in a novel vdW heterostructure combining hexagonal boron nitride (hBN) and vanadium dioxide (VO 2 ). It is observed that the insulator-to-metal transition in VO 2 has a profound impact on the polaritons in the proximal hBN layer. In effect, the real-space propagation of hyperbolic polaritons and their spectroscopic resonances can be actively controlled by temperature. This tunability originates from the effective change in local dielectric properties of the VO 2 sublayer in the course of the temperature-tuned insulator-to-metal phase transition. The high susceptibility of polaritons to electronic phase transitions opens new possibilities for applications of vdW materials in combination with strongly correlated quantum materials.
Bibliographical noteFunding Information:
S.D. and J.Z. contributed equally to this work. Work at Columbia University on optical phenomena in vdW materials is supported by DOE-BES DE-FG02-00ER45799 and Betty Moore Foundation’s EPiQS Initiative through Grant GBMF4533. Q.M. and P.J.-H. were supported by the Center for Excitonics, an Energy Frontier Research Center funded by the DOE, Office of Science, BES under Award Number DESC0001088 and AFOSR Grant FA9550-16-1-0382, as well as the Gordon and Betty Moore Foundation’s EPiQS Initiative through Grant GBMF4541 to P.J.-H.
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- hexagonal boron nitride
- phase-change materials