Amazing stuff! Good vibrations!
"A pioneering team ... has captured the first-ever images of atomic thermal vibrations, unlocking an unseen world of motion within two-dimensional materials. Their innovative electron ptychography technique revealed elusive “moiré phasons,” a long-theorized phenomenon that governs heat, electronic behavior, and structural order at the atomic level. This discovery not only confirms decades-old theories but also provides a new lens for building the future of quantum computing, ultra-efficient electronics, and advanced nanosensors. ..."
"Researchers investigating atomic-scale phenomena impacting next-generation electronic and quantum devices have captured the first microscopy images of atomic thermal vibrations—revealing a new type of motion that could reshape the design of quantum technologies and ultrathin electronics. ...
developed an electron microscopy technique to directly image “moiré phasons”—a physical phenomenon that impacts superconductivity and heat conduction in two-dimensional materials for next-generation electronic and quantum devices. ..."
From the abstract of the perspective:
"Twisted heterostructures—two atomically thin layers stacked at an angle by van der Waals forces—exhibit exotic properties beyond those of each layer alone, such as superconductivity.
The interlayer interactions cause structural reconstruction of atoms within the layers, forming a Moiré superlattice. This lattice has distinctive vibrational modes, called Moiré phonons (or phasons), that affect the material’s properties. However, low energy (~0.01 meV) and nanometer-scale spatial variation make the characterization of phasons with existing techniques extremely challenging. ...
Zhang et al. report the use of a computational imaging technique, called electron ptychography, to characterize phasons in twisted bilayers of tungsten diselenide. The findings illustrate how the extreme spatial resolution offered by electron ptychography can yield insights into a phenomenon that would be otherwise difficult to study."
From the editor's summary and abstract:
"Editor’s summary
The collective vibrations of a low-twist-angle moiré superlattice of tungsten diselenide were imaged with high-resolution electron ptychography. The rotationally aligned regions in these superlattices are separated by networks of stacking faults that can host ultrasoft shear modes, or phasons, with frequencies less than one wavenumber that are inaccessible using conventional vibrational spectroscopy. Imaging by Zhang et al. at a resolution of under 15 picometers revealed that these spatially localized, anisotropic vibrations dominated the thermal vibrations ...
Abstract
Twisted two-dimensional materials exhibit distinctive vibrational modes called moiré phonons, which arise from the moiré superlattice.
Here, we demonstrate atom-by-atom imaging of phasons, an ultrasoft class of moiré phonons in twisted bilayer tungsten diselenide (WSe2).
Using ultrahigh-resolution (<15 picometers) electron ptychography, we imaged the size and shape of each atom to extract time-averaged vibrational amplitudes as a function of twist angle and position.
We observed several signature properties of moiré phasons, such as increased vibrational amplitudes at solitons and AA-stacked regions. By correlating experiments with molecular dynamics simulations and lattice dynamics calculations, we show that phasons dominate the thermal vibrations in low-angle twisted bilayers. These results represent a powerful route to image thermal vibrations at atomic resolution, unlocking experimental studies of a thus far hidden branch of moiré phonon physics."
Scientists Document First Images of the Atomic Fingerprint of Heat in Quantum Materials (original news release)
Minuscule vibrations, uncovered (no public access) "Computational imaging resolves atomic vibrations at picometer scale"
Atom-by-atom imaging of moiré phasons with electron ptychography (no public access)
Atom-by-atom Imaging of Moiré Phasons using Electron Ptychography (preprint, open access)
The lead author Yichao Zhang
No comments:
Post a Comment