Exotic bonding interactions and coexistence of chemically distinct periodic lattice distortions in the charge density wave compound TaTe2

2020 ◽  
Vol 102 (2) ◽  
Author(s):  
Valeri Petkov ◽  
Kamal Chapagain ◽  
Junjie Yang ◽  
Sarvjit Shastri ◽  
Yang Ren
Keyword(s):  
Charge Density ◽  
Charge Density Wave ◽  
Density Wave ◽  
Periodic Lattice ◽  
Lattice Distortions

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.

scholarly journals Microscopic evidence for strong periodic lattice distortion in two-dimensional charge-density wave systems

2014 ◽  
Vol 89 (16) ◽  
Author(s):  
Jixia Dai ◽  
Eduardo Calleja ◽  
Jacob Alldredge ◽  
Xiangde Zhu ◽  
Lijun Li ◽  
...  
Keyword(s):  
Charge Density ◽  
Charge Density Wave ◽  
Lattice Distortion ◽  
Density Wave ◽  
Periodic Lattice ◽  
Two Dimensional ◽  
Microscopic Evidence

Periodic lattice distortion accompanying the charge-density-wave transition for Sn/Ge(111)

1999 ◽  
Vol 60 (4) ◽  
pp. 2860-2863 ◽  
Author(s):  
Jiandi Zhang ◽  
Ismail ◽  
P. J. Rous ◽  
A. P. Baddorf ◽  
E. W. Plummer
Keyword(s):  
Charge Density ◽  
Charge Density Wave ◽  
Lattice Distortion ◽  
Density Wave ◽  
Periodic Lattice

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 ◽  
Transition Period ◽  
Density Wave ◽  
Domain Growth ◽  
Periodic Lattice ◽  
Coherent Phonon ◽  
Linear Defects ◽  
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>, static Rayleigh-phonon coupling to periodic lattice distortions (PLDs), as well as incommensurate (IC) domain growth and coarsening over the first 100 ps following femtosecond photoexcitation, suggests ultrafast, displacively-excited coherent acoustic phonons (CAPs) may strongly couple to PLDs. Here we find evidence for such coupling using 4D ultrafast electron microscopy (UEM). For ultrathin room-temperature crystals, photoinduced Bragg-peak dynamics spanning the first 75 ps are characterized by partial CAP coherence and localized low-amplitude <i>c</i>-axis dilations. These relatively weak, partially-coherent dynamics then give way to higher-amplitude, increasingly-coherent oscillations, the transition period of which is well-matched to timescales of photoinduced IC domain growth and stabilization from the nearly-commensurate (NC) phase. Diffraction experiments are correlated with nanoscale UEM imaging, where it is found that phonon wave trains emerge from nanoscale linear defects 100 ps after photoexcitation. The CAPs consist of coupled longitudinal and transverse character and propagate at an anomalously-high 4.6 nm/ps along wave vectors independent from NC-phase PLDs, instead being dictated by static defect orientation. Such behaviors illustrate a potential means to control phases in quantum materials using defect-engineered coherent-phonon seeding.<br>

Periodic lattice distortion accompanying the(3×3)charge-density-wave phase of Sn/Ge(111)

1998 ◽  
Vol 57 (8) ◽  
pp. 4579-4583 ◽  
Author(s):  
A. P. Baddorf ◽  
V. Jahns ◽  
Jiandi Zhang ◽  
J. M. Carpinelli ◽  
E. W. Plummer
Keyword(s):  
Charge Density ◽  
Charge Density Wave ◽  
Lattice Distortion ◽  
Density Wave ◽  
Periodic Lattice ◽  
Wave Phase ◽  
Charge Density Wave Phase

Satellite Dark Field Microscopy of Charge Density Wave Domains in Transition-Metal Dichalcogenides

1980 ◽  
Vol 38 ◽  
pp. 338-339
Author(s):  
K. K. Fung ◽  
J. W. Steeds
Keyword(s):  
Transition Metal ◽  
Charge Density ◽  
Density Wave ◽  
Transition Metal Dichalcogenides ◽  
Dark Field ◽  
Charge Density Waves ◽  
Periodic Lattice ◽  
Dark Field Microscopy ◽  
Metal Dichalcogenides ◽  
Lattice Distortions

Transition-metal dichalcogenides are layer compounds which exhibit anomalies in their transport properties at low temperatures. Diffraction studies have shown that the anomalies are associated with the formation of charge density waves (CDW) coupled to periodic lattice distortions (1). This is manifested as satellite spots decorating Bragg reflections. The satellite spots can be used to image the structure associated with the CDW transitions in dark field. This is accomplished by tilting the specimen so that a satellite spot is strongly excited. In this way, we have imaged domains in the incommensurate and commensurate states of transition-metal dichalcogenides. The existence of CDW domains has been predicted theoretically (2). Using a commercial single-tilting hot stage and a liquid-helium-cooled double-tilting stage built in this laboratory in a Philips EM400 microscope we have studied the nature of domains in several IT polytype transition-metal dichalcogenides between 40K and 600K.

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