scholarly journals Mechanisms of electron-phonon coupling unraveled in momentum and time: The case of soft phonons in TiSe2

2021 ◽  
Vol 7 (20) ◽  
pp. eabf2810
Author(s):  
Martin R. Otto ◽  
Jan-Hendrik Pöhls ◽  
Laurent P. René de Cotret ◽  
Mark J. Stern ◽  
Mark Sutton ◽  
...  
Keyword(s):  
Wave Vector ◽  
Density Wave ◽  
Phonon Coupling ◽  
Many Body ◽  
Soft Zone ◽  
Electron Phonon Coupling ◽  
Underlying Mechanisms ◽  
The Many ◽  
Coupling Phenomena ◽  
Electron Pocket

The complex coupling between charge carriers and phonons is responsible for diverse phenomena in condensed matter. We apply ultrafast electron diffuse scattering to unravel electron-phonon coupling phenomena in 1T-TiSe2 in both momentum and time. We are able to distinguish effects due to the real part of the many-body bare electronic susceptibility, R[χ0(q)], from those due to the electron-phonon coupling vertex, gq, by following the response of semimetallic (normal-phase) 1T-TiSe2 to the selective photo-doping of carriers into the electron pocket at the Fermi level. Quasi-impulsive and wave vector–specific renormalization of soft zone-boundary phonon frequencies (stiffening) is observed, followed by wave vector–independent electron-phonon equilibration. These results unravel the underlying mechanisms driving the phonon softening that is associated with the charge density wave transition at lower temperatures.

scholarly journals Wave-vector-dependent electron-phonon coupling and the charge-density-wave transition inTbTe3

2015 ◽  
Vol 91 (23) ◽  
Author(s):  
M. Maschek ◽  
S. Rosenkranz ◽  
R. Heid ◽  
A. H. Said ◽  
P. Giraldo-Gallo ◽  
...  
Keyword(s):  
Charge Density ◽  
Wave Vector ◽  
Charge Density Wave ◽  
Density Wave ◽  
Phonon Coupling ◽  
Electron Phonon Coupling

scholarly journals Charge order lock-in by electron-phonon coupling in La1.675Eu0.2Sr0.125CuO4

2021 ◽  
Vol 7 (27) ◽  
pp. eabg7394
Author(s):  
Qisi Wang ◽  
Karin von Arx ◽  
Masafumi Horio ◽  
Deepak John Mukkattukavil ◽  
Julia Küspert ◽  
...  
Keyword(s):  
Wave Vector ◽  
Charge Order ◽  
Charge Ordering ◽  
Electron Interaction ◽  
Phonon Coupling ◽  
Electron Phonon Interaction ◽  
Self Energy ◽  
Electron Phonon Coupling ◽  
Charge Stripe ◽  
Lock In

Charge order is universal to all hole-doped cuprates. Yet, the driving interactions remain an unsolved problem. Electron-electron interaction is widely believed to be essential, whereas the role of electron-phonon interaction is unclear. We report an ultrahigh-resolution resonant inelastic x-ray scattering (RIXS) study of the in-plane bond-stretching phonon mode in stripe-ordered cuprate La1.675Eu0.2Sr0.125CuO4. Phonon softening and lifetime shortening are found around the charge ordering wave vector. In addition to these self-energy effects, the electron-phonon coupling is probed by its proportionality to the RIXS cross section. We find an enhancement of the electron-phonon coupling around the charge-stripe ordering wave vector upon cooling into the low-temperature tetragonal structure phase. These results suggest that, in addition to electronic correlations, electron-phonon coupling contributes substantially to the emergence of long-range charge-stripe order in cuprates.

scholarly journals Ultrafast electron calorimetry uncovers a new long-lived metastable state in 1T-TaSe2 mediated by mode-selective electron-phonon coupling

2019 ◽  
Vol 5 (3) ◽  
pp. eaav4449 ◽  
Author(s):  
Xun Shi ◽  
Wenjing You ◽  
Yingchao Zhang ◽  
Zhensheng Tao ◽  
Peter M. Oppeneer ◽  
...  
Keyword(s):  
Heat Capacity ◽  
Metastable State ◽  
Density Wave ◽  
Charge Order ◽  
Phonon Coupling ◽  
Phonon Modes ◽  
Angle Resolved Photoemission Spectroscopy ◽  
Quantum Matter ◽  
Electron Phonon Coupling ◽  
Equilibrium Phases

Quantum materials represent one of the most promising frontiers in the quest for faster, lightweight, energy-efficient technologies. However, their inherent complexity and rich phase landscape make them challenging to understand or manipulate. Here, we present a new ultrafast electron calorimetry technique that can systematically uncover new phases of quantum matter. Using time- and angle-resolved photoemission spectroscopy, we measure the dynamic electron temperature, band structure, and heat capacity. This approach allows us to uncover a new long-lived metastable state in the charge density wave material 1T-TaSe2, which is distinct from all the known equilibrium phases: It is characterized by a substantially reduced effective total heat capacity that is only 30% of the normal value, because of selective electron-phonon coupling to a subset of phonon modes. As a result, less energy is required to melt the charge order and transform the state of the material than under thermal equilibrium conditions.

scholarly journals Electronic nature of charge density wave and electron-phonon coupling in kagome superconductor KV3Sb5

2022 ◽  
Vol 13 (1) ◽  
Author(s):  
Hailan Luo ◽  
Qiang Gao ◽  
Hongxiong Liu ◽  
Yuhao Gu ◽  
Dingsong Wu ◽  
...  
Keyword(s):  
Electronic Structure ◽  
Fermi Surface ◽  
Charge Density ◽  
Charge Density Wave ◽  
Density Wave ◽  
Phonon Coupling ◽  
Electronic Nature ◽  
Electron Phonon Coupling ◽  
Gap Opening ◽  
Fermi Surface Reconstruction

AbstractThe Kagome superconductors AV3Sb5 (A = K, Rb, Cs) have received enormous attention due to their nontrivial topological electronic structure, anomalous physical properties and superconductivity. Unconventional charge density wave (CDW) has been detected in AV3Sb5. High-precision electronic structure determination is essential to understand its origin. Here we unveil electronic nature of the CDW phase in our high-resolution angle-resolved photoemission measurements on KV3Sb5. We have observed CDW-induced Fermi surface reconstruction and the associated band folding. The CDW-induced band splitting and the associated gap opening have been revealed at the boundary of the pristine and reconstructed Brillouin zones. The Fermi surface- and momentum-dependent CDW gap is measured and the strongly anisotropic CDW gap is observed for all the V-derived Fermi surface. In particular, we have observed signatures of the electron-phonon coupling in KV3Sb5. These results provide key insights in understanding the nature of the CDW state and its interplay with superconductivity in AV3Sb5 superconductors.

scholarly journals Band-selective Holstein polaron in Luttinger liquid material A0.3MoO3 (A = K, Rb)

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
L. Kang ◽  
X. Du ◽  
J. S. Zhou ◽  
X. Gu ◽  
Y. J. Chen ◽  
...  
Keyword(s):  
Charge Density ◽  
Electronic Properties ◽  
Charge Density Wave ◽  
Density Wave ◽  
Luttinger Liquid ◽  
Phonon Coupling ◽  
Strong Electron ◽  
One Dimensional ◽  
Molybdenum Blue ◽  
Electron Phonon Coupling

Abstract(Quasi-)one-dimensional systems exhibit various fascinating properties such as Luttinger liquid behavior, Peierls transition, novel topological phases, and the accommodation of unique quasiparticles (e.g., spinon, holon, and soliton, etc.). Here we study molybdenum blue bronze A0.3MoO3 (A = K, Rb), a canonical quasi-one-dimensional charge-density-wave material, using laser-based angle-resolved photoemission spectroscopy. Our experiment suggests that the normal phase of A0.3MoO3 is a prototypical Luttinger liquid, from which the charge-density-wave emerges with decreasing temperature. Prominently, we observe strong renormalizations of band dispersions, which are recognized as the spectral function of Holstein polaron derived from band-selective electron-phonon coupling in the system. We argue that the strong electron-phonon coupling plays an important role in electronic properties and the charge-density-wave transition in blue bronzes. Our results not only reconcile the long-standing heavy debates on the electronic properties of blue bronzes but also provide a rare platform to study interesting excitations in Luttinger liquid materials.

scholarly journals Enhanced Electron-Phonon Coupling for Charge-Density-Wave Formation in La1.8−xEu0.2SrxCuO4+δ

2020 ◽  
Vol 125 (9) ◽  
Author(s):  
Y. Y. Peng ◽  
A. A. Husain ◽  
M. Mitrano ◽  
S. X.-L. Sun ◽  
T. A. Johnson ◽  
...  
Keyword(s):  
Charge Density ◽  
Charge Density Wave ◽  
Density Wave ◽  
Wave Formation ◽  
Phonon Coupling ◽  
Electron Phonon Coupling

scholarly journals Anomalously Suppressed Thermal Conduction by Electron‐Phonon Coupling in Charge‐Density‐Wave Tantalum Disulfide

2020 ◽  
Vol 7 (11) ◽  
pp. 1902071 ◽  
Author(s):  
Huili Liu ◽  
Chao Yang ◽  
Bin Wei ◽  
Lei Jin ◽  
Ahmet Alatas ◽  
...  
Keyword(s):  
Charge Density ◽  
Charge Density Wave ◽  
Thermal Conduction ◽  
Density Wave ◽  
Phonon Coupling ◽  
Electron Phonon Coupling

scholarly journals Electron-phonon coupling in the C60fullerene within the many-bodyGWapproach

2011 ◽  
Vol 84 (15) ◽  
Author(s):  
Carina Faber ◽  
Jonathan Laflamme Janssen ◽  
Michel Côté ◽  
E. Runge ◽  
X. Blase
Keyword(s):  
Phonon Coupling ◽  
Electron Phonon Coupling ◽  
The Many

PAIRING AND SPONTANEOUS POLARIZATION IN DENSE HYDROGEN

1999 ◽  
Vol 13 (05n06) ◽  
pp. 595-605 ◽  
Author(s):  
N. W. ASHCROFT
Keyword(s):  
Charge Density ◽  
Electron Gas ◽  
Density Wave ◽  
Functional Integral ◽  
Integral Representations ◽  
Many Body ◽  
Starting Point ◽  
The Many ◽  
A Charge ◽  
The Continuum

The many-body problem associated with dense hydrogen can represented by the standard interacting electron gas problem (complete with compensating charge continuum) augmented by the proton equivalent and a coupling between the two. This viewpoint is useful as a starting point in the pursuit of ground-state instabilities (particularly the onset of a charge density wave) as a function of the continuum charge density, and even more generally in the identification of forms for the fields required to establish a thermodynamic treatment via coherent state functional integral representations of the partition function for dense hydrogen.

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