Observation of a Charge Density Wave Incommensuration Near the Superconducting Dome in 
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Kogar, Anshul; Peña, G. A. de la; Lee, Sang-Jun; Fang, Yizhi; Sun, Stella; Lioi, David B.; Karapetrov, G.; Finkelstein, Ken; Ruff, Jacob P. C.; Abbamonte, Peter; Rosenkranz, S.

doi:10.1103/physrevlett.118.027002

Cited by 92 publications

(96 citation statements)

References 28 publications

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“…It is these domain wall regions where superconductivity is found to nucleate keeping these two independent orders (i.e., sSC and CDW) spatially apart. It is only such ICDW ordering tendencies which were found to coexist with sSC [29,31]. Naturally, such an incommensurate CDW phase lacks a long range coherence.…”

Section: Introductionmentioning

confidence: 95%

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Emergent superconductivity upon disordering a charge density wave ground state

2018

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We explore the interplay of a charge density wave (CDW) order and s-wave superconductivity (sSC) in a disordered system. Recent experiments on 1T-TiSe2, where the pristine sample has a commensurate CDW order and the superconductivity appears upon copper intercalation, motivates our study. Starting with an extended Hubbard model, with parameters which yield a CDW ground state within Hartree-Fock-Bogoliubov formalism in pure systems, we show that the addition of disorder quickly wipes out the global charge order by disrupting periodic modulation of density at some (low) strength of disorder. Along with this, the subdominant superconducting order emerges in regions that spatially anti-correlates with islands of strong local CDW order. The short-range density modulations, however, continue to persist and show discernible effects up to a larger disorder strength. The local CDW puddles reduce in size with increasing disorder and they finally lose their relevance in effecting the properties of the system. Our results have strong implications for the experimental phase diagram of transition metal dichalcogenides.

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Section: Introductionmentioning

confidence: 95%

“…Surprisingly, the initial rapid decay of CDW order slows down considerably beyond dopings which marks the onset of superconductivity, and an incommensurate charge density wave (ICDW) order survives beyond this point. Such ICDW phase is found to persist along with superconductivity at doping as large as x ≈ 0.11 [31,32].…”

Section: Introductionmentioning

confidence: 95%

Emergent superconductivity upon disordering a charge density wave ground state

2018

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“…5(f) shows a sharp peak centred at T c in the second derivative, although we note that discerning this peak in practice may often be complicated by the amplification of experimental noise in such second derivative analysis. Identifying the CDW onset temperature in TiSe 2 may, in general, therefore require additional measurements such as specific heat [2], or the observation of superlattice reflections in scattering measurements [31].…”

Section: Criteria For the Determination Of Cdw Temperaturementioning

confidence: 99%

On the origin of the anomalous peak in the resistivity of TiSe2

2019

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Resistivity measurements of TiSe2 typically show only a weak change in gradient at the charge density wave transition at TCDW ≈ 200 K, but more prominently feature a broad peak at a lower T peak ∼ 165 K, which has remained poorly understood despite decades of research on the material. Here we present quantitative simulations of the resistivity using a simplified parametrization of the normal state band structure, based on recent photoemission data. Our simulations reproduce the overall profile of the resistivity of TiSe2, including its prominent peak, without implementing the CDW at all. We find that the peak in resistivity corresponds to a crossover between a low temperature regime with electron-like carriers only, to a regime around room temperature where thermally activated and highly mobile hole-like carriers dominate the conductivity. Even when implementing substantial modifications to model the CDW below the transition temperature, we find that these thermal population effects still dominate the transport properties of TiSe2.Phase transitions such as charge density waves (CDWs) are often first characterized by the observation of anomalies in resistivity measurements. Such phase transitions can influence the resistivity via Fermi surface reconstructions, changes in scattering rates, and/or a loss of free carriers due to the formation of an energy gap. However in TiSe 2 , which exhibits a much-studied CDW-like phase transition at T CDW ≈ 200 K [1, 2], transport measurements show a highly unusual and non-monotonic temperature-dependence. Samples which are close to stoichiometry typically show n-type metallic-like behavior at low temperatures, followed by a prominent broad peak at T peak ∼165 K, distinct from T CDW , beyond which the resistivity decreases with increasing temperature in a semiconductor-like fashion, with a positive Hall coefficient at room temperature [1]. Surprisingly little change occurs at T CDW , with at most a modest change in slope observed at ≈200 K [1, 3], even though the CDW involves changes to the band structure on energy scales as large as 100 meV [4]. The resistivity is known to be highly sensitive to the sample stoichiometry, and the observation of the anomalous broad peak at T peak ∼165 K in resistivity measurements has sometimes been taken as an indicator of sample quality [1,3,5,6]. On the other hand, some studies have interpreted the peak feature as a signature of the role of excitons in the CDW ordering [7][8][9][10][11]. Given the resurgence of interest in TiSe 2 in recent years, it is worthwhile to revisit the long-standing problem of its unusual transport properties [5,[12][13][14], aided by the availability of recent characterizations of its 3D electronic structure by angle-resolved photoemission spectroscopy (ARPES) [15].In this paper, we show that the overall temperaturedependence of the resistivity of TiSe 2 , including the anomalous peak, can be reasonably reproduced without accounting for the CDW at all. Our model is very simple, but it captures the essential ingredien...

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“…Therefore, given the strong similarity between the electronic impact of Cu and Ti on the CDW when intercalated within the 1T -TiSe 2 vdW gap [36,59], an open question remains as to the extent to which the disorder introduced by native low-concentration Ti defects is detrimental for the emergence of superconductivity in Cu-intercalated crystals. In any case, it calls for considering an additional self-doping axis in the associated phase diagram [9] and opens the door for further exploration.…”

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confidence: 99%

Phase separation in the vicinity of Fermi surface hot spots

et al. 2019

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Spatially inhomogeneous electronic states are expected to be key ingredients for the emergence of superconducting phases in quantum materials hosting charge-density-waves (CDWs). Prototypical materials are transition-metal dichalcogenides (TMDCs) and among them, 1T -TiSe2 exhibiting intertwined CDW and superconducting states under Cu intercalation, pressure or electrical gating. Although it has been recently proposed that the emergence of superconductivity relates to CDW fluctuations and the development of spatial inhomogeneities in the CDW order, the fundamental mechanism underlying such a phase separation (PS) is still missing. Using angle-resolved photoemission spectroscopy and variable-temperature scanning tunneling microscopy, we report on the phase diagram of the CDW in 1T -TiSe2 as a function of Ti self-doping, an overlooked degree of freedom inducing CDW texturing. We find an intrinsic tendency towards electronic PS in the vicinity of Fermi surface (FS) "hot spots", i.e. locations with band crossings close to, but not at the Fermi level. We therefore demonstrate an intimate relationship between the FS topology and the emergence of spatially textured electronic phases which is expected to be generalizable to many doped CDW compounds.

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Observation of a Charge Density Wave Incommensuration Near the Superconducting Dome in CuxTiSe2

Cited by 92 publications

References 28 publications

Emergent superconductivity upon disordering a charge density wave ground state

Emergent superconductivity upon disordering a charge density wave ground state

On the origin of the anomalous peak in the resistivity of TiSe2

Phase separation in the vicinity of Fermi surface hot spots

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