Visualizing the melting of periodic lattice distortions in a complex 2D charge density wave material via MeV-scale ultrafast electron diffraction

2021 ◽  
Author(s):  
Khalid M. Siddiqui ◽  
Daniel B. Durham ◽  
Frederick Cropp ◽  
Sangeeta Rajpurohit ◽  
Colin Ophus ◽  
...  
Keyword(s):  
Electron Diffraction ◽  
Charge Density ◽  
Charge Density Wave ◽  
Density Wave ◽  
Periodic Lattice ◽  
Ultrafast Electron Diffraction ◽  
Lattice Distortions

scholarly journals Direct Electron-Diffraction Evidence of Charge-Density-Wave Formation in NbSe3

1977 ◽  
Vol 39 (26) ◽  
pp. 1675-1676 ◽  
Author(s):  
K. Tsutsumi ◽  
T. Takagaki ◽  
M. Yamamoto ◽  
Y. Shiozaki ◽  
M. Ido ◽  
...  
Keyword(s):  
Electron Diffraction ◽  
Charge Density ◽  
Charge Density Wave ◽  
Density Wave ◽  
Wave Formation

scholarly journals Coherent Phonon Disruption and Lock-In During a Photoinduced Charge-Density-Wave Phase Transition

2021 ◽  
Author(s):  
Spencer A. Reisbick ◽  
Yichao Zhang ◽  
Jialiang Chen ◽  
Paige Engen ◽  
David Flannigan
Keyword(s):  
Charge Density ◽  
Charge Density Wave ◽  
Degrees Of Freedom ◽  
Structural Phase ◽  
Density Wave ◽  
Optical Excitation ◽  
Partial Coherence ◽  
Periodic Lattice ◽  
Coherent Phonon ◽  
Quantum Materials

Ultrafast manipulation of phases and phase domains in quantum materials is a key approach to unraveling and harnessing interwoven effects of charge and lattice degrees of freedom. In the intensely-studied charge-density-wave (CDW) material, 1<i>T</i>-TaS<sub>2</sub>, phonon coupling to periodic lattice distortions (PLDs) and atomically-incoherent picosecond structural phase transitions suggest transitional periods could exist for delayed onset of mode coherence. Here we find evidence for such a connection between displacively-excited coherent acoustic phonons and PLDs using 4D ultrafast electron microscopy. Following femtosecond optical excitation of an ultrathin crystal, a propagating hybridized mode is imaged emerging from linear defects within a 1-μm region. Partial coherence and low amplitudes during onset of the incommensurate phase convert to higher-amplitude, increasingly-coherent oscillations as phase-growth stabilizes. The hybrid mode consists of large out-of-plane distortions coupled to basal-plane bond oscillations propagating at anomalously high velocities. The strongly-correlated behaviors observed here represent a potential means to control phase behaviors in quantum materials using defect-engineered coherent-phonon seeding.

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