Optical Control of Multistage Phase Transition via Phonon Coupling in MoTe2

2022 ◽  
Vol 128 (1) ◽  
Author(s):  
Meng-Xue Guan ◽  
Xin-Bao Liu ◽  
Da-Qiang Chen ◽  
Xuan-Yi Li ◽  
Ying-Peng Qi ◽  
...  
2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Kwangrae Kim ◽  
Hoon Kim ◽  
Jonghwan Kim ◽  
Changil Kwon ◽  
Jun Sung Kim ◽  
...  

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.


Author(s):  
Guannan Qu ◽  
Meijiao Sun ◽  
Shuo Li ◽  
Chenglin Sun ◽  
Tianyuan Liu ◽  
...  

2019 ◽  
Vol 99 (22) ◽  
Author(s):  
M. J. Neugebauer ◽  
T. Huber ◽  
M. Savoini ◽  
E. Abreu ◽  
V. Esposito ◽  
...  

1999 ◽  
Vol 86 (11) ◽  
pp. 5927-5934 ◽  
Author(s):  
Hyoung-Kwan Lee ◽  
Akihiko Kanazawa ◽  
Takeshi Shiono ◽  
Tomiki Ikeda ◽  
Toru Fujisawa ◽  
...  

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Jiaji Ma ◽  
Ruihan Yang ◽  
Hanghui Chen

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.


1980 ◽  
Vol 100 (2) ◽  
pp. 659-663 ◽  
Author(s):  
M. Ya. Valakh ◽  
Y. A. Veshka ◽  
M. P. Lisitsa ◽  
G. S. Svechnikov ◽  
V. P. Pinzenik

2018 ◽  
Vol 20 (36) ◽  
pp. 23656-23663 ◽  
Author(s):  
Hang Zhai ◽  
Zhen Qin ◽  
Dan Sun ◽  
Jianyun Wang ◽  
Chang Liu ◽  
...  

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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