Superconductivity and hybrid soft modes in<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mi>Ti</mml:mi><mml:msub><mml:mi>Se</mml:mi><mml:mn>2</mml:mn></mml:msub></mml:mrow></mml:math>

Maschek, M.; Rosenkranz, S.; Hott, R.; Heid, R.; Merz, Michael; Zocco, D. A.; Said, Ayman; Alataş, Ahmet; Karapetrov, G.; Zhu, Shixin; Wezel, Jasper van; Weber, F.

doi:10.1103/physrevb.94.214507

Cited by 29 publications

(20 citation statements)

References 61 publications

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“…For TbTe3 and GdTe3, a sharp increase of to 3 − 4 K occurs above 4 GPa , which was suggested to originate from either a loss of broken spatial symmetry at an orthorhombic-to-tetragonal structural phase transition intrinsic to the RTe3 system, or by percolation of superconducting tellurium impurities above 5 GPa. While the detailed − phase diagram of RTe3 is not fully determined, we have shown in a work concerning the CDW material TiSe2 and CuxTiSe2 that a phase diagram featuring a superconducting phase emerging around the critical point where the CDW order is suppressed to zero temperature can be explained by electron-phonon coupling when the CDW soft phonon mode is also responsible for mediating superconductivity [34].…”

Section: Discussionmentioning

confidence: 90%

“…Ideally, one would like to perform phonon calculations in the distorted structure corresponding to the experimental situation at 𝑇𝑇 𝐶𝐶𝐶𝐶𝐶𝐶,2 < 𝑇𝑇 < 𝑇𝑇 𝐶𝐶𝐶𝐶𝐶𝐶,1 . However, while we were able to perform such calculations for the superstructure of the commensurate CDW compound 1T-TiSe2 [34], the required supercells for any approximation of the incommensurate CDW order in DyTe3 are too large for comparable lattice dynamical calculations.…”

Section: A Theorymentioning

confidence: 99%

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Competing soft phonon modes at the charge-density-wave transitions in DyTe3

et al. 2018

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The family of rare-earth tritellurides RTe3 features charge-density-wave (CDW) order related to strongly momentum-dependent electron-phonon coupling. Similar to other CDW compounds, superconductivity is observed when the CDW order is suppressed via hydrostatic pressure [1]. What sets the heavier members of the RTe3 series apart is the observation of a second CDW transition at lower temperatures having an in-plane ordering wavevector , ∥ [ ] of almost the same magnitude but orthogonal to the ordering wavevector , ∥ [ ] observed at higher temperatures [2]. Here, we report an inelastic x-ray scattering investigation of the lattice dynamics of DyTe3. In particular, we show that there are several phonon modes along both in-plane directions, which respond to the onset of the CDW transition at , =. Surprisingly, these soft modes close to , = ( . , , ) show strong softening near , but do not exhibit any response to the lower-temperature transition at , = . Our results indicate that the low-temperature CDW order is not just the 90° rotated analogue of the one appearing at high temperatures.

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Section: Discussionmentioning

confidence: 90%

Section: A Theorymentioning

confidence: 99%

Competing soft phonon modes at the charge-density-wave transitions in DyTe3

et al. 2018

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“…[6,16,17] In particular for 1T-TiSe 2 there are arguments that an electron-lattice deformation [5,[18][19][20] or an excitonic insulator mechanism [21][22][23][24][25][26][27][28][29][30] is responsible, but the prevailing explanation is a combination of both. [19,20,24,[27][28][29][31][32][33][34][35][36][37][38][39] Besides excitonic and Peierls insulators, other metal-insulator transitions such as Mott insulators have been extensively investigated, too. [40][41][42][43] Progress in time-and angle-resolved photoemission spectroscopy (trARPES) has made it possible to investigate the ultrafast non-equilibrium material response after optical excitation.…”

Section: Introductionmentioning

confidence: 99%

Optical amplification in a CDW-phase of a quasi-two dimensional material

Michael,

Schneider

2021

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We study theoretically the quenching of a charge-density-wave phase in a model system of a quasi-two dimensional material, which includes both electron-hole and electron-phonon interactions leading, respectively to excitonic and coherent-phonon contributions. We discuss how interaction processes affect anomalous expectation values and present a microscopic dynamical picture of the quenching of the phase. We use projection techniques to illustrate the time-dependent appearance of additional bands and anomalous expectation values. We propose an optical amplification effect with a high modulation frequency in the mid-infrared regime.

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“…[17] Kogar et al performed X-ray diffraction experiments on Cu x TiSe 2 and proposed that the incommensuration and domain walls of the CDW may play a crucial role in the formation of the SC state as in the pressure induced SC mentioned above. [18] On the other hand, Kitou et al [14] and Maschek et al [19] stressed the dissimilarity between the doping induced and pressure induced cases. For instance, Maschek et al argued that the doping induced SC can be understood by the phonon mediated pairing mechanism alone while a hybridization of phonon and exciton modes is necessary for the pressure induced SC.…”

Section: Introductionmentioning

confidence: 99%

The maximal superconductivity in proximity to charge density wave quantum critical point in Cu$_x$TiSe$_2$

Park,

Uzoh,

Choi

2021

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Superconductivity emerges in 1T -TiSe2 when its charge density wave (CDW) order is suppressed by Cu intercalation or pressure. Since the CDW state is thought to be an excitonic insulator, an interesting question is whether the superconductivity is also mediated by the excitonic fluctuations. We investigated this question as to the nature of doping induced superconductivity in CuxTiSe2 by asking if it is consistent with the phonon-mediated pairing. We employed the ab initio density functional theory and density functional perturbation theory to compute the electron-phonon coupling Eliashberg function from which to calculate the superconducting (SC) critical temperature Tc. The calculated Tc as a function of the doping concentration x exhibits a dome shape with the maximum Tc of 2 − 6 K at x ≈ 0.05 for the Coulomb pseudopotential 0 ≤ µ * ≤ 0.1. The maximal Tc was found to be pinned to the quantum critical point at which the CDW is completely suppressed and the corresponding phonon mode becomes soft. Underlying physics is that the reduced phonon frequency enhances the electron-phonon coupling constant λ which overcompensates the frequency decrease to produce a net increase of Tc. The doping induced superconductivity in CuxTiSe2 seems to be consistent with the phonon-mediated pairing. Comparative discussion was made with the pressure induced superconductivity in TiSe2.

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Superconductivity and hybrid soft modes inTiSe2

Abstract: The competition between superconductivity and other ground states of solids is one of the challenging topics in condensed matter physics. Apart from high-temperature superconductors

Cited by 29 publications

References 61 publications

Competing soft phonon modes at the charge-density-wave transitions in DyTe3

Competing soft phonon modes at the charge-density-wave transitions in DyTe3

Optical amplification in a CDW-phase of a quasi-two dimensional material

The maximal superconductivity in proximity to charge density wave quantum critical point in Cu$_x$TiSe$_2$

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