scholarly journals Electron-phonon coupling and electronic thermoelectric properties of n -type PbTe driven near the soft-mode phase transition via lattice expansion

2021 ◽  
Vol 104 (4) ◽  
Author(s):  
Jiang Cao ◽  
Đorđe Dangić ◽  
José D. Querales-Flores ◽  
Stephen Fahy ◽  
Ivana Savić
Keyword(s):  
Phase Transition ◽  
Thermoelectric Properties ◽  
Soft Mode ◽  
Lattice Expansion ◽  
Phonon Coupling ◽  
Electron Phonon Coupling

Effect of Electron-Phonon Coupling on Transport Properties of Monolayers of ZrS2, BiI3 and PbI2: A thermoelectric Perspective

2021 ◽  
Author(s):  
Gautam Sharma ◽  
Vineet Kumar Pandey ◽  
Shouvik Datta ◽  
Prasenjit Ghosh
Keyword(s):  
Relaxation Time ◽  
Band Structure ◽  
Transport Properties ◽  
Thermoelectric Properties ◽  
Thermoelectric Materials ◽  
Waste Heat ◽  
Transport Coefficients ◽  
Electrical Energy ◽  
Phonon Coupling ◽  
Electron Phonon Coupling

Thermoelectric materials are used for conversion of waste heat to electrical energy. The transport coefficients that determine their thermoelectric properties depend on the band structure and the relaxation time of...

scholarly journals Direct observation of excitonic instability in Ta2NiSe5

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Kwangrae Kim ◽  
Hoon Kim ◽  
Jonghwan Kim ◽  
Changil Kwon ◽  
Jun Sung Kim ◽  
...  
Keyword(s):  
Phase Transition ◽  
Direct Observation ◽  
Structural Phase ◽  
Temperature Phase ◽  
Phonon Coupling ◽  
Strong Electron ◽  
Weiss Temperature ◽  
Excitonic Insulator ◽  
Electron Phonon Coupling ◽  
Low Temperature Phase

AbstractCoulomb attraction between electrons and holes in a narrow-gap semiconductor or a semimetal is predicted to lead to an elusive phase of matter dubbed excitonic insulator. However, direct observation of such electronic instability remains extremely rare. Here, we report the observation of incipient divergence in the static excitonic susceptibility of the candidate material Ta2NiSe5 using Raman spectroscopy. Critical fluctuations of the excitonic order parameter give rise to quasi-elastic scattering of B2g symmetry, whose intensity grows inversely with temperature toward the Weiss temperature of TW ≈ 237 K, which is arrested by a structural phase transition driven by an acoustic phonon of the same symmetry at TC = 325 K. Concurrently, a B2g optical phonon becomes heavily damped to the extent that its trace is almost invisible around TC, which manifests a strong electron-phonon coupling that has obscured the identification of the low-temperature phase as an excitonic insulator for more than a decade. Our results unambiguously reveal the electronic origin of the phase transition.

Phase-transition induced changes in the electron–phonon coupling of all-trans-β-carotene

2013 ◽  
Vol 104 ◽  
pp. 92-96 ◽  
Author(s):  
Guannan Qu ◽  
Meijiao Sun ◽  
Shuo Li ◽  
Chenglin Sun ◽  
Tianyuan Liu ◽  
...  
Keyword(s):  
Phase Transition ◽  
Phonon Coupling ◽  
Electron Phonon Coupling ◽  
Induced Changes ◽  
Β Carotene

Wilson's Numerical Renormalization Group Calculation of the Anderson–Holstein Model: Phonon Propagator

2003 ◽  
Vol 17 (18n20) ◽  
pp. 3381-3386 ◽  
Author(s):  
Han-Yong Choi ◽  
Tae-Ho Park ◽  
Gun Sang Jeon
Keyword(s):  
Renormalization Group ◽  
Phonon Mode ◽  
Soft Mode ◽  
Coulomb Repulsion ◽  
Zero Temperature ◽  
Coupling Constant ◽  
Phonon Coupling ◽  
Improved Method ◽  
Numerical Renormalization Group ◽  
Electron Phonon Coupling

We study the symmetric Anderson–Holstein (AH) model at zero temperature with Wilson's numerical renormalization group (NRG) technique to study the interplay between the electron-electron and electron-phonon interactions. An improved method for calculating the phonon propagator using the NRG technique is presented and applied to the AH model as the onsite Coulomb repulsion U and electron-phonon coupling constant g are varied. As g is increased, the phonon propagator is successively renormalized, and for g≳gco crosses over to the regime where the mode splits into two components, one of which approaches back to the bare frequency and the other develops into a soft mode. The initial renormalization of the phonon mode, as g is increased from 0, can be either positive or negative depending on U and the hybridization Δ.

scholarly journals A large modulation of electron-phonon coupling and an emergent superconducting dome in doped strong ferroelectrics

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Jiaji Ma ◽  
Ruihan Yang ◽  
Hanghui Chen
Keyword(s):  
Phase Transition ◽  
First Principles ◽  
Critical Concentration ◽  
Phonon Coupling ◽  
Total Electron ◽  
Epitaxial Strain ◽  
Itinerant Electrons ◽  
Weakly Coupled ◽  
Electron Phonon Coupling ◽  
Viable Approach

AbstractWe use first-principles methods to study doped strong ferroelectrics (taking BaTiO3 as a prototype). Here, we find a strong coupling between itinerant electrons and soft polar phonons in doped BaTiO3, contrary to Anderson/Blount’s weakly coupled electron mechanism for "ferroelectric-like metals”. As a consequence, across a polar-to-centrosymmetric phase transition in doped BaTiO3, the total electron-phonon coupling is increased to about 0.6 around the critical concentration, which is sufficient to induce phonon-mediated superconductivity of about 2 K. Lowering the crystal symmetry of doped BaTiO3 by imposing epitaxial strain can further increase the superconducting temperature via a sizable coupling between itinerant electrons and acoustic phonons. Our work demonstrates a viable approach to modulating electron-phonon coupling and inducing phonon-mediated superconductivity in doped strong ferroelectrics and potentially in polar metals. Our results also show that the weakly coupled electron mechanism for "ferroelectric-like metals” is not necessarily present in doped strong ferroelectrics.

scholarly journals Detecting electron-phonon coupling during photoinduced phase transition

2021 ◽  
Vol 103 (12) ◽  
Author(s):  
Takeshi Suzuki ◽  
Yasushi Shinohara ◽  
Yangfan Lu ◽  
Mari Watanabe ◽  
Jiadi Xu ◽  
...  
Keyword(s):  
Phase Transition ◽  
Phonon Coupling ◽  
Electron Phonon Coupling

Pressure-induced phase transition, metallization and superconductivity in ZrS2

2018 ◽  
Vol 20 (36) ◽  
pp. 23656-23663 ◽  
Author(s):  
Hang Zhai ◽  
Zhen Qin ◽  
Dan Sun ◽  
Jianyun Wang ◽  
Chang Liu ◽  
...  
Keyword(s):  
Phase Transition ◽  
High Pressure ◽  
Phonon Coupling ◽  
Band Structures ◽  
Electronic Band ◽  
Electron Phonon Coupling ◽  
Electronic Band Structures ◽  
Stable Structures

The high-pressure thermodynamically stable structures of ZrS2 have been extensively identified using an effective CALYPSO algorithm. Our theoretical electronic band structures and electron–phonon coupling unravel the occurrence of pressure-induced metallization and superconductivity in ZrS2.

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