The electronic structure formation of Cu<i>x</i>TiSe2 in a wide range (0.04 &amp;lt; <i>x</i> &amp;lt; 0.8) of copper concentration

Shkvarin, A. S.; Yarmoshenko, Yu. M.; Yablonskikh, M. V.; Меренцов, А. И.; Shkvarina, E. G.; Titov, A. N.; Zhukov, Yu. M.; Титов, А. Ф.

doi:10.1063/1.4941767

Cited by 24 publications

(22 citation statements)

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“…Stripe charge order has been observed by STM in other layered compounds [2,35,36] and was attributed to local strain. Strain could play a role here as a consequence of the reported 1T-TiSe 2 unit cell expansion when intercalating Cu [37].…”

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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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confidence: 99%

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

et al. 2017

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“…This is in a good agreement with the fact that the change in the Cu concentration in Cu x TiSe 2 did not affect the Ti 2p spectra. 20 The Cu 2p spectra shown in Fig. 8 (left panel) are almost identical to those for the Cu x TiSe 2 system 20 and correspond to the Cu 0 or Cu I charge state.…”

Section: Xpsmentioning

confidence: 62%

“…6) are specially sensitive to the changes in phase composition and surface quality. 20,25 Even at low Ni concentration (x = 0.14), a shift towards higher binding energies is observed (see Table 4). According to ref.…”

Section: Xpsmentioning

confidence: 93%

“…Details of their synthesis have been reported elsewhere. 19,20 The synchrotron radiation X-ray photoelectron (XPS), X-ray absorption (XAS) and resonant X-ray photoelectron (ResPES) spectra for Ni 0.14 TiSe 2 , Cu 0.13 Ni 0.43 TiSe 2 and Cu 0.2 Ni 0.25 TiSe 2 were obtained on the CNR IOM BACH beamline 21 at the Elettra synchrotron facility (Trieste, Italy). Linearly-polarized X-rays with a polarization vector 601 off the surface plane were used.…”

Section: Methodsmentioning

confidence: 99%

“…This is in good agreement with previously obtained data for the Cu x TiSe 2 system for x o 0.2, where Cu intercalation also did not affect the shift of the Se 3d line. 20 Probably, the increase in the Se 3d binding energy is not the result of an electron transfer from Cu to the lattice, but the result of redistribution of the Ni atoms due to the Cu intercalation.…”

Section: Xpsmentioning

confidence: 99%

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