Point-contact tunneling spectroscopy measurement of<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:msub><mml:mi>Cu</mml:mi><mml:mi>x</mml:mi></mml:msub><mml:msub><mml:mi>TiSe</mml:mi><mml:mn>2</mml:mn></mml:msub></mml:mrow></mml:math>: Disorder-enhanced Coulomb effects

Luna, Katherine; Wu, Phillip M.; Chen, Justin S.; Morosan, Emilia; Beasley, M. R.

doi:10.1103/physrevb.91.094509

Cited by 7 publications

(13 citation statements)

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“…Only an estimate of 𝑇𝑇 𝑐𝑐 can be given, because the value of the effective electron-electron interaction potential 𝜇𝜇 * is not calculated within DFPT. For the estimated values shown in Figure 2d, we used 𝜇𝜇 * = 0.1, which was also used in previous calculations of 𝑇𝑇 𝑐𝑐 in superconducting TiSe2 [15] and 𝜇𝜇 * = 0.15 based on a recent experimental work on CuxTiSe2 [36]. We find the maximum values of 𝑇𝑇 𝑐𝑐 very close to the critical point of the CDW phase (Fig.…”

Section: 𝒒𝒒𝜗𝜗mentioning

confidence: 65%

Superconductivity and hybrid soft modes inTiSe2

et al. 2016

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Section: 𝒒𝒒𝜗𝜗mentioning

confidence: 65%

Superconductivity and hybrid soft modes inTiSe2

et al. 2016

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“…Here, we demonstrate a direct link between the Cu content and the observed band shift. The origin of the weak singularity at E F , also observed in pointcontact tunneling [33], remains to be firmly established. It is most likely not a real DOS feature but a manifestation of electron-electron interaction and impurity scattering expected in disordered metals [34], with disorder due to intercalated Cu and Ti.…”

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confidence: 99%

Stripe and Short Range Order in the Charge Density Wave of 1T−CuxTiSe2

et al. 2017

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We study the impact of Cu intercalation on the charge density wave (CDW) in 1T-Cu x TiSe 2 by scanning tunneling microscopy and spectroscopy. Cu atoms, identified through density functional theory modeling, are found to intercalate randomly on the octahedral site in the van der Waals gap and to dope delocalized electrons near the Fermi level. While the CDW modulation period does not depend on Cu content, we observe the formation of charge stripe domains at low Cu content (x < 0.02) and a breaking up of the commensurate order into 2 × 2 domains at higher Cu content. The latter shrink with increasing Cu concentration and tend to be phase shifted. These findings invalidate a proposed excitonic pairing as the primary CDW formation mechanism in this material. DOI: 10.1103/PhysRevLett.118.017002 Correlated electron systems are prone to develop distinct electronic ground states, such as superconductivity, charge density waves (CDWs), and spin ordered phases. The nature of the interplay between these ground states is the focus of intense research efforts. A CDW is a spatial modulation of the electron density associated with local lattice distortions. CDWs are found in a number of quasitwo-dimensional superconductors, including transition metal dichalcogenides [1], intercalated graphite [2], cuprates [3-5] and pnictides [6]. Of particular interest, largely driven by the puzzle of high temperature superconductivity, is whether charge order is competing, cooperating, or simply coexisting with superconductivity [7]. The layered transition metal dichalcogenide 1T-TiSe 2 offers an attractive playground to explore the interplay between these two electronic ground states, thus potentially contributing to resolving similar outstanding questions in cuprate superconductors and other strongly correlated materials.1T-TiSe 2 consists of a stack of van der Waals (vdW) coupled layers allowing in situ preparation of surfaces ideally suited for scanning probe investigations by cleaving. When cooled below T CDW ≃ 200 K, it undergoes a second-order phase transition into a commensurate 2 × 2 × 2 CDW superlattice [8,9]. There is currently no consensus on the origin of the CDW in this material. Two possible scenarios are being considered, one based on a purely electronic process characterized by an excitonic instability [8], while the other one involves a Jahn-Teller (JT) distortion [10]. More refined theories also propose a mixture of these two possible contributions, in the so called indirect JT transition [11][12][13].1T-TiSe 2 becomes superconducting when intercalating more than x ¼ 0.04 copper into the vdW gap, with a maximum critical temperature T c ¼ 4.1 K near x ¼ 0.08 [14]. Transport measurements [14,15] indicate the CDW is suppressed upon increasing the Cu content which would suggest a competition with superconductivity. A more recent report of an incommensurate CDW above the superconducting dome in pristine crystals under pressure [16] suggests a more complex scenario, where CDW fluctuations promote superconductivity. Traces of ...

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“…We first repeat in a slightly different form our major results. We take equation (14) and omit the third term on the right hand side (the third term is dΣ x B (ǫ)/dǫ). We get…”

Section: Discussion Alternative View On Theorymentioning

confidence: 99%

“…U co where U co is a characteristic correlation energy. The DOS ∝ |E − E F | at energies |E − E F | U co was observed by tunneling spectroscopy [4][5][6][7][8][9][10][11][12][13][14] and by photoemission spectroscopy [15]. Some experiments [8-10, 12, 15] studied the DOS also for |E − E F | > U co .…”

Section: Introductionmentioning

confidence: 99%

“…[1,17] the integral in equation ( 8) was calculated assuming V (q) ≃ V (0). For V (q) = V (0) the integral diverges in the upper limit, therefore, the upper limit was restricted to q max = | ǫ | / D. Since V (q) ≃ V (0) only for q k s , the obtained result [equation ( 11 Within this approach the term ρ(E F ) remains undetermined, it is usually determined experimentally [14,15].…”

Section: Introductionmentioning

confidence: 99%

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States-conserving density of states for Altshuler-Aronov effect: Heuristic derivation

Mošková

Moško

2018

Solid State Communications

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Altshuler and Aronov (AA) have shown that the electron-electron interaction in a weakly-disordered metal suppresses the single-particle density of states (DOS) in the vicinity of the Fermi level (EF ). According to the AA theory the suppressed DOS exhibits the energy dependence ∝ |E − EF | valid for |E − EF | smaller than a certain correlation energy Uco. Recent experiments have shown that at energies larger than Uco the DOS exhibits a states-conserving dependence on energy, namely, the states removed from near the Fermi level are found at energies above Uco in the energy range of about 3Uco. In this work the AA effect is studied beyond the low energy limit theoretically. We consider the AA model in which the electrons interact via the statically screened Coulomb interaction and the modification of the DOS is due to the exchange part of the electron selfenergy. We derive the states-conserving DOS heuristically. Namely, we show that the self-energy consists of a diverging part (which we skip on physical grounds) and of the small part of the order of the pair Coulomb energy. This small part gives the states-conserving DOS which is in qualitative accord with experimental observations at energies above Uco and which reproduces the AA result at energies below Uco.

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Point-contact tunneling spectroscopy measurement ofCuxTiSe2: Disorder-enhanced Coulomb effects

Cited by 7 publications

References 20 publications

Superconductivity and hybrid soft modes inTiSe2

Superconductivity and hybrid soft modes inTiSe2

Stripe and Short Range Order in the Charge Density Wave of 1T−CuxTiSe2

States-conserving density of states for Altshuler-Aronov effect: Heuristic derivation

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