Structural distortion and electronic states of Rb doped WO3 by X-ray absorption spectroscopy

RSC Advances ◽  
2016 ◽  
Vol 6 (109) ◽  
pp. 107871-107877 ◽  
Author(s):  
Y. C. Wang ◽  
C. H. Hsu ◽  
Y. Y. Hsu ◽  
C. C. Chang ◽  
C. L. Dong ◽  
...  
Keyword(s):  
Structural Phase ◽  
Electronic States ◽  
Phonon Coupling ◽  
Structural Phase Transitions ◽  
Superconducting Properties ◽  
Strong Electron ◽  
X Ray ◽  
Electron Phonon Coupling ◽  
Complex Structural ◽  
X Ray Absorption

Rubidium tungsten bronzes (RbxWO3) have recently attracted much attention due to their intriguing phenomena, such as complex structural phase transitions, strong electron–phonon coupling, and superconducting properties.

scholarly journals Structural phase transition and superconductivity hierarchy in 1T-TaS2 under pressure up to 100 GPa

2021 ◽  
Vol 6 (1) ◽  
Author(s):  
Qing Dong ◽  
Quanjun Li ◽  
Shujia Li ◽  
Xuhan Shi ◽  
Shifeng Niu ◽  
...  
Keyword(s):  
Structural Phase ◽  
Transition Metal Dichalcogenides ◽  
Phonon Coupling ◽  
Structural Phase Transitions ◽  
Strong Electron ◽  
Electron Phonon Coupling ◽  
Increasing Trend ◽  
Metal Dichalcogenides ◽  
Dome Shape ◽  
Enhanced Superconductivity

AbstractThe adoption of high pressure not only reinforces the comprehension of the structure and exotic electronic states of transition metal dichalcogenides (TMDs) but also promotes the discovery of intriguing phenomena. Here, 1T-TaS2 was investigated up to 100 GPa, and re-enhanced superconductivity was found with structural phase transitions. The discovered I4/mmm TaS2 presents strong electron–phonon coupling, revealing a good superconductivity of the nonlayered structure. The P–T phase diagram shows a dome shape centered at ~20 GPa, which is attributed to the distortion of the 1T structure. Accompanied by the transition to nonlayered structure above 44.5 GPa, the superconducting critical temperature shows an increasing trend and reaches ~7 K at the highest studied pressure, presenting superior superconductivity compared to the original layered structure. It is unexpected that the pressure-induced re-enhanced superconductivity was observed in TMDs, and the transition from a superconductor with complicated electron-pairing mechanism to a phonon-mediated superconductor would expand the field of pressure-modified superconductivity.

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.

scholarly journals On the Superconductivity Suppression in Eu1−xPrxBa2Cu3O7−δ

Materials ◽  
2021 ◽  
Vol 14 (13) ◽  
pp. 3503
Author(s):  
Paweł Pęczkowski ◽  
Piotr Zachariasz ◽  
Cezariusz Jastrzębski ◽  
Jarosław Piętosa ◽  
Elżbieta Drzymała ◽  
...  
Keyword(s):  
Raman Spectroscopy ◽  
Low Temperature ◽  
Magnetic Moment ◽  
Schematic Diagram ◽  
Optical Phonons ◽  
Phonon Coupling ◽  
X Ray Diffraction ◽  
X Ray ◽  
Electron Phonon Coupling ◽  
X Ray Absorption

This article reports on the non-trivial suppression of superconductivity in the Eu1−xPrxBCO cuprates. As non-magnetic Eu3+ ions are replaced by Pr3+ carrying a magnetic moment, spin-related superconductivity loss can be expected. The research shows that the superconductivity disappearance for x > 0.4 results from depletion of the carriers and their localization. The above conclusion was drawn by low-temperature X-ray diffraction analysis showing increased characteristic phonon frequencies with Pr content. This mechanism should promote electron–phonon coupling, at least for acoustic phonons. However, the inverse phenomenon was detected. Namely, there is a gradual deterioration of the optical phonons responsible for vibration of the Cu–O bonds with Pr increasing, as evidenced by Raman spectroscopy. Furthermore, the results of X-ray absorption spectroscopy precisely showed the location of the carriers for Pr-rich specimens. Finally, a schematic diagram for Eu1−xPrxBCO is proposed to consolidate the presented research.

Temperature-induced structural phase transitions in RERhSn (RE = Y, Gd-Tm, Lu)

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Simon Engelbert ◽  
Rolf-Dieter Hoffmann ◽  
Jutta Kösters ◽  
Steffen Klenner ◽  
Rainer Pöttgen
Keyword(s):  
Rare Earth ◽  
Phase Transitions ◽  
Driving Force ◽  
Room Temperature ◽  
Structural Phase ◽  
Structural Phase Transitions ◽  
Line Broadening ◽  
X Ray Diffraction ◽  
Temperature Dependent ◽  
X Ray

Abstract The structures of the equiatomic stannides RERhSn with the smaller rare earth elements Y, Gd-Tm and Lu were reinvestigated on the basis of temperature-dependent single crystal X-ray diffraction data. GdRhSn crystallizes with the aristotype ZrNiAl at 293 and 90 K. For RE = Y, Tb, Ho and Er the HP-CeRuSn type (approximant with space group R3m) is already formed at room temperature, while DyRhSn adopts the HP-CeRuSn type below 280 K. TmRhSn and LuRhSn show incommensurate modulated variants with superspace groups P31m(1/3; 1/3; γ) 000 (No. 157.1.23.1) (γ = 3/8 for TmRhSn and γ = 2/5 for LuRhSn). The driving force for superstructure formation (modulation) is a strengthening of Rh–Sn bonding. The modulation is expressed in a 119Sn Mössbauer spectrum of DyRhSn at 78 K through line broadening.

History and Cross-Disciplinary Perspective of Compositional Imaging and Mapping With Nexafs Microscopy

1998 ◽  
Vol 4 (S2) ◽  
pp. 154-155
Author(s):  
H. Ade
Keyword(s):  
Electronic Structures ◽  
Chemical Shifts ◽  
Electronic States ◽  
Inorganic Materials ◽  
Chemical Bonds ◽  
Fundamental Physics ◽  
X Ray ◽  
Disciplinary Perspective ◽  
Core Electrons ◽  
X Ray Absorption

In Near Edge X-ray Absorption Fine Structure (NEXAFS) microscopy, excitations of core electrons into unoccupied molecular orbitals or electronic states provide sensitivity to a wide variety of chemical functionalities in molecules and solids. This sensitivity complements infrared (IR) spectroscopy, although the NEXAFS spectra are not quite as specific and “rich” as IR spectra. The sensitivity of NEXAFS to distinguish chemical bonds and electronic structures covers a wide variety of samples: from metals to inorganics and organics. (There is a tendency in the community to use the term NEXAFS for soft x-ray spectroscopy of organic materials, while for inorganic materials or at higher energies X-ray Absorption Near Edge Spectroscopy (XANES) is utilized, even though the fundamental physics is the same.) The sensitivity of NEXAFS is particularly high to distinguish saturated from unsaturated bonds. NEXAFS can also detect conjugation in a molecule, as well as chemical shifts due to heteroatoms.

Strong electron-phonon coupling at a metal/organic interface: PTCDA/Ag(111)

2002 ◽  
Vol 65 (12) ◽  
Author(s):  
F. S. Tautz ◽  
M. Eremtchenko ◽  
J. A. Schaefer ◽  
M. Sokolowski ◽  
V. Shklover ◽  
...  
Keyword(s):  
Phonon Coupling ◽  
Strong Electron ◽  
Electron Phonon Coupling ◽  
Metal Organic

scholarly journals Intriguing light-emission features of ketoprofen-based Eu(III) adduct due to a strong electron–phonon coupling

2016 ◽  
Vol 170 ◽  
pp. 357-363 ◽  
Author(s):  
M.G. Lahoud ◽  
R.C.G. Frem ◽  
D.A. Gálico ◽  
G. Bannach ◽  
M.M. Nolasco ◽  
...  
Keyword(s):  
Light Emission ◽  
Phonon Coupling ◽  
Strong Electron ◽  
Electron Phonon Coupling
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