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 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 ON THE PHONON-INDUCED SUPERCONDUCTIVITY OF DISORDERED ALLOYS

1996 ◽  
Vol 10 (20) ◽  
pp. 2469-2529 ◽  
Author(s):  
A.O. ANOKHIN ◽  
M.I. KATSNELSON
Keyword(s):  
Effective Interaction ◽  
Energy Scale ◽  
Phonon Interaction ◽  
Interaction Kernel ◽  
Generating Functional ◽  
Electron Phonon Interaction ◽  
Self Energy ◽  
Disordered Alloys ◽  
Electron Phonon Coupling ◽  
Alloy Part

A model of alloy is considered which includes both quenched disorder in the electron subsystem (“alloy” subsystem) and electron-phonon interaction. For given approximate solution for the alloy part of the problem, which is assumed to be conserving in Baym’s sense, we construct the generating functional and derive the Eliashberg-type equations which are valid to the lowest order in the adiabatic parameter. The renormalization of bare electron–phonon interaction vertices by disorder is taken into account consistently with the approximation for the alloy self-energy. For the case of exact configurational averaging the same set of equations is established within the usual T-matrix approach. We demonstrate that for any conserving approximation for the alloy part of the self-energy the Anderson’s theorem holds in the case of isotropic singlet pairing provided disorder renormalizations of the electron-phonon interaction vertices are neglected. Taking account of the disorder renormalization of the electron-phonon interaction we analyze general equations qualitatively and present the expressions for Tc for the case of weak and intermediate electron-phonon coupling. Disorder renormalizations of the logarithmic corrections to the effective coupling, which arise when the effective interaction kernel for the Cooper channel has the second energy scale, as well as the renormalization of the dilute paramagnetic impurity suppression are discussed.

PATH-INTEGRAL APPROACH FOR ELECTRON–PHONON INTERACTION EFFECTS IN HARMONIC QUANTUM DOTS

1996 ◽  
Vol 10 (22) ◽  
pp. 2781-2796 ◽  
Author(s):  
SOMA MUKHOPADHYAY ◽  
ASHOK CHATTERJEE
Keyword(s):  
Quantum Dots ◽  
Path Integral ◽  
State Energy ◽  
Coupling Parameter ◽  
Three Dimensions ◽  
Integral Approach ◽  
Phonon Coupling ◽  
Electron Phonon Interaction ◽  
Electron Phonon Coupling ◽  
Parabolic Confinement

We use the Feynman–Haken path-integral formalism to obtain the polaronic correction to the ground state energy of an electron in a polar semiconductor quantum dot with parabolic confinement in both two and three dimensions. We perform calculations for the entire range of the electron–phonon coupling parameter and for arbitrary confinement length. We apply our results to several semiconductor quantum dots and show that the polaronic effect in some of these dots can be considerably large if the dot sizes are made smaller than a few nanometers.

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 Self-energy effects and electron–phonon coupling in Fe–As superconductors

2010 ◽  
Vol 22 (11) ◽  
pp. 115802 ◽  
Author(s):  
K-Y Choi ◽  
P Lemmens ◽  
I Eremin ◽  
G Zwicknagl ◽  
H Berger ◽  
...  
Keyword(s):  
Phonon Coupling ◽  
Self Energy ◽  
Electron Phonon Coupling

INFLUENCE OF ELECTRON–PHONON INTERACTION ON EFFECTIVE MASS IN SOME HEAVY FERMION (HF) SYSTEMS

2008 ◽  
Vol 22 (04) ◽  
pp. 365-379 ◽  
Author(s):  
S. MOHANTY ◽  
B. K. KALTA ◽  
P. NAYAK
Keyword(s):  
Effective Mass ◽  
Coupling Strength ◽  
Heavy Fermion ◽  
Simple Expression ◽  
Model Parameters ◽  
Coupling Mechanism ◽  
Phonon Coupling ◽  
Phonon Interaction ◽  
Electron Phonon Interaction ◽  
Electron Phonon Coupling

It is a fact that for ordinary metals, the electron–phonon interaction increases the quasi-particle mass, which is in contrast to the finding by Fulde et al. that, for some heavy Fermion (HF) systems, it decreases. Some experiments on HF systems suggest that there exists a strong coupling of the elastic degrees of freedom with these at the electronic and magnetic ones. To understand the effect of electron–phonon interaction on effective mass, the electron–phonon coupling mechanism in the framework of the periodic Anderson model is considered, and a simple expression is derived. This involves various model parameters namely, the position of the 4f level; the effective coupling strength, g, temperature, b; and the electron–phonon coupling strength, r. The influence of these parameters on the value of effective mass is studied, and interesting results were found. For simplicity, the numerical calculation is performed in the long wavelength limit.

EFFECTS OF ELECTRON–PHONON INTERACTION IN TUNNELING PROCESSES IN NANOSTRUCTURES

2007 ◽  
Vol 06 (05) ◽  
pp. 411-414
Author(s):  
P. I. ARSEYEV ◽  
N. S. MASLOVA
Keyword(s):  
Phonon Coupling ◽  
Phonon Interaction ◽  
Strong Electron ◽  
Resonant Case ◽  
Electron Phonon Interaction ◽  
Electron Phonon Coupling ◽  
Tunneling Conductivity ◽  
Nonequilibrium Effects ◽  
Inelastic Tunneling

Tunneling through a system with two discrete electron levels coupled by electron–phonon interaction is considered. The interplay between elastic and inelastic tunneling channels is analyzed for a strong electron–phonon coupling in the resonant case. It is shown that the intensity and the width of peaks in tunneling conductivity are strongly influenced by nonequilibrium effects.

Investigations of the Thermal Shifts and Electron–Phonon Coupling Parameters of R1 and R2 Lines for Cr3+-doped Forsterite

2014 ◽  
Vol 69 (8-9) ◽  
pp. 497-500 ◽  
Author(s):  
Xiao-Xuan Wu ◽  
Wen-Chen Zheng
Keyword(s):  
Thermal Expansion ◽  
Spectral Lines ◽  
Coupling Coefficients ◽  
Phonon Coupling ◽  
Lattice Thermal Expansion ◽  
Phonon Interaction ◽  
Electron Phonon Interaction ◽  
Electron Phonon Coupling ◽  
Coupling Parameters ◽  
Vibrational Contribution

The thermal shifts of R1 and R2 lines in Cr3+-doped forsterite (Mg2SiO4) are studied by considering both the static contribution due to lattice thermal expansion and the vibrational contribution due to electron-phonon interaction. In the studies, the thermal expansion coefficient of the Cr3+ center is assumed reasonably as that of the corresponding cluster in the host crystal. The results suggest that for R1 and R2 lines the static contributions are opposite in sign and in magnitude about 37% and 45%, respectively, of the corresponding vibrational contributions. The true electron-phonon coupling coefficients α' (obtained by considering both contributions) increase by about 58% and 81%, respectively, for R1 and R2 lines in comparison with the corresponding parameters α obtained by considering only the vibrational contribution. It appears that for the reasonable explanation of thermal shift of spectral lines and the exact estimation of electron-phonon coupling coefficient, both the static and vibrational contributions should be taken into account

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