Publications by authors named "Yoseob Yoon"

Article Synopsis
  • Phonon engineering at gigahertz frequencies supports applications like microwave acoustic filters and quantum transducers, while terahertz phonon engineering promises faster and higher bandwidth technologies.
  • Researchers demonstrated effective generation, detection, and manipulation of terahertz phonons using atomically thin materials, specifically few-layer graphene and monolayer WSe, within van der Waals heterostructures.
  • The study showcases high-quality terahertz phononic cavities and the ability of WSe embedded in hexagonal boron nitride to block terahertz phonon transmission, paving the way for advanced acoustic filters and thermal engineering techniques.
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Ultrafast charge transfer processes provide a facile way to create interlayer excitons in directly contacted transition metal dichalcogenide (TMD) layers. More sophisticated heterostructures composed of TMD/hBN/TMD enable new ways to control interlayer exciton properties and achieve novel exciton phenomena, such as exciton insulators and condensates, where longer lifetimes are desired. In this work, we experimentally study the charge transfer dynamics in a heterostructure composed of a 1 nm thick hBN spacer between MoSe and WSe monolayers.

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Article Synopsis
  • Moiré patterns in transition metal dichalcogenide heterobilayers can host unique correlated electronic phases and exciton physics, but their microscopic nature is not well understood.
  • Using advanced computational techniques and micro-reflection spectroscopy, researchers identified new exciton resonances in WSe/WS moiré superlattices that go beyond existing models.
  • The study reveals diverse excitonic behaviors, including modulated Wannier excitons and novel charge-transfer excitons, with potential implications for controlling many-body physics in these systems.
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Electron tunneling spectroscopy is a powerful technique to probe the unique physical properties of one-dimensional (1D) single-walled carbon nanotubes (SWNTs), such as the van Hove singularities in the density of states or the power-law tunneling probability of a Luttinger liquid. However, little is known about the tunneling behavior between two 1D SWNTs over a large energy spectrum. Here, we investigate the electron tunneling behavior between two crossed SWNTs across a wide spectral window up to 2 eV in the unique carbon nanotube-hexagonal boron nitride-carbon nanotube heterojunctions.

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The ideas of topology have found tremendous success in closed physical systems, but even richer properties exist in the more general open or dissipative framework. We theoretically propose and experimentally demonstrate a bulk Fermi arc that develops from non-Hermitian radiative losses in an open system of photonic crystal slabs. Moreover, we discover half-integer topological charges in the polarization of far-field radiation around the bulk Fermi arc.

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The experimental realization of Bose-Einstein condensation (BEC) with atoms and quasiparticles has triggered wide exploration of macroscopic quantum effects. Microcavity polaritons are of particular interest because quantum phenomena such as BEC and superfluidity can be observed at elevated temperatures. However, polariton lifetimes are typically too short to permit thermal equilibration.

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