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Batlogg, B.; Cava, R. J.; Jayaraman, A.; Dover, R. B. van; Kourouklis, G. A.; Sunshine, Steven A.; Murphy, D. W.; Rupp, L. W.; Chen, H. S.; White, Alice E.; Short, K. T.; Mujsce, A. M.; Rietman, Edward A.

doi:10.1103/physrevlett.58.2333

Cited by 531 publications

(89 citation statements)

References 26 publications

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“…The optimally doped material has the corresponding minimum ␣ of 3.5 ϫ 10 Ϫ3 . An early study on YBa 2 Cu 3 O 7 gives a value of ␣ of 0 Ϯ 0.02 (4). Another careful examination of five pairs of YBa 2 Cu 3 O 7 samples (6) gives an oxygen isotope effect of ␣ ϭ 0.017 Ϯ 0.006.…”

Section: [3]mentioning

confidence: 99%

Unified picture of the oxygen isotope effect in cuprate superconductors

Chen

Struzhkin

et al. 2007

Proc. Natl. Acad. Sci. U.S.A.

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High-temperature superconductivity in cuprates was discovered almost exactly 20 years ago, but a satisfactory theoretical explanation for this phenomenon is still lacking. The isotope effect has played an important role in establishing electron-phonon interaction as the dominant interaction in conventional superconductors. Here we present a unified picture of the oxygen isotope effect in cuprate superconductors based on a phonon-mediated d-wave pairing model within the Bardeen-Cooper-Schrieffer theory. We show that this model accounts for the magnitude of the isotope exponent as functions of the doping level as well as the variation between different cuprate superconductors. The isotope effect on the superconducting transition is also found to resemble the effect of pressure on the transition. These results indicate that the role of phonons should not be overlooked for explaining the superconductivity in cuprates.electron-phonon interaction ͉ high-temperature superconductivity ͉ pressure effect U nderstanding the high-temperature superconductivity in cuprate superconductors is at the heart of current research in solid-state physics. The isotope effect is an important experimental probe in revealing the underlying pairing mechanism of superconductivity. Early measurements (1) of the isotope effect on the superconducting transition temperature, T c , provided key experimental evidence for phonon-mediated pairing and supported strongly the Bardeen-Cooper-Schrieffer (BCS) theory of superconductivity in conventional materials. When hightemperature superconductivity was discovered in copper oxides, the oxygen isotope exponents, defined by ␣ ' ϪdlnT c /dlnM, with M being the isotopic mass, were promptly measured. The initial finding of the small value of ␣ in La 1.85 Sr 0.15 CuO 4 (2, 3) and near zero value in YBa 2 Cu 3 O 7Ϫ␦ (␦ ϳ 0) (4-6) was taken to be convincing evidence against electron-phonon interaction as the dominant mechanism in these materials. However, later experiments have revealed a much richer and more complex situation (7). There is a striking variation of ␣ with doping level in a given cuprate material (8-11). Meanwhile, ␣ also varies among various compounds of different cuprate families (7,12). Interestingly, ␣ is a remarkably monotonic function of the number of CuO 2 layers in a way opposite to T c in optimally doped compounds (12). Such elaborate isotope effects strongly suggest that one should include phonons in the theory of high-T c superconductivity. Studies of neutron scattering (13), angleresolved photoemission spectroscopy (14, 15), and scanning transmission electron microscopy (16) provide further evidence for phonons being an important player in the basic physics of high-T c superconductivity.Compared with isotope substitution, pressure has been realized not only to be another effective way to change T c for a superconductor (17) but also to yield information on the interaction causing the superconductivity. So far, the record high T c of 164 K was achieved under high pressure in HgBa 2 C...

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Section: [3]mentioning

confidence: 99%

Unified picture of the oxygen isotope effect in cuprate superconductors

Chen

Struzhkin

et al. 2007

Proc. Natl. Acad. Sci. U.S.A.

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“…The oxygen isotope effect on T c was found [11] to be small, with α(T c ) ≈ 0.06. However, with decreasing doping the effect rises and eventually diverges as T c → 0 [12,13].…”

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confidence: 99%

Isotope Effect in the Superfluid Density of High-Temperature Superconducting Cuprates: Stripes, Pseudogap, and Impurities

et al. 2005

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Underdoped cuprates exhibit a normal-state pseudogap, and their spins and doped carriers tend to spatially separate into 1-or 2-D stripes. Some view these as central to superconductivity, others as peripheral and merely competing. Using La2−xSrxCu1−yZnyO4 we show that an oxygen isotope effect in Tc and in the superfluid density can be used to distinguish between the roles of stripes and pseudogap and also to detect the presence of impurity scattering. We conclude that stripes and pseudogap are distinct, and both compete and coexist with superconductivity.PACS numbers: 71.10. Hf, 74.25.Dw, 74.62.Dh, 74.72.Dn High-T c superconductors (HTS) remain a puzzle. Various correlated states have been identified in HTS including antiferromagnetism, the pseudogap[1], nanoscale spin-charge stripes [2] and, of course, superconductivity (SC). (Here we generalise"stripes" to include possible 2D checkerboard structures [3]). The pseudogap is a nodal energy gap of uncertain origin that appears in the normal-state (NS) density of states (DOS). Its effects can be observed in many physical properties [1,4]. Several opposing views are still current. One is that stripes play a central role [5], forming the pseudogap correlation [6] and/or mediating the SC pairing. Another is that the NS pseudogap arises from incoherent superconducting fluctuations which set in well above T c [7]. Another is that these states are independently competing [8]. Here stripes and pseudogap play a secondary role and SC is mediated by some other pairing boson. An unambiguous test of these opposing views is urgently needed. We show here that isotope effects provide such a test.The isotope exponent α(E) in a given property E is defined as α(E) = − (∆E/E)/(∆M/M ), where M is the isotopic mass and E may be T c , the SC gap parameter, ∆ 0 , the pseudogap energy scale, E g , or the superfluid density ρ s = λ −2 ab = µ 0 e 2 (n s /m * ab ). (λ ab is the in-plane London penetration depth, n s is the carrier density and m * ab is the effective electronic mass for in-plane transport). An isotope effect on T c was first discovered in 1950 by Allen et al. for Sn [9]. They found α(T c ) ≈ 0.5 ± 0.05 which provided the central clue for the role of phonons in pairing and led 7 years later to the BCS theory of SC [10].The situation with HTS is more complex. The oxygen isotope effect on T c was found[11] to be small, with α(T c ) ≈ 0.06. However, with decreasing doping the effect rises and eventually diverges as T c → 0[12, 13]. Surprisingly, an isotope effect was also found in the superfluid density [14] (and attempts were made to resolve this into a dominant isotope effect just in m * [15,16]). We will show that both of these unusual effects can be understood in terms of a normal-state pseudogap which competes with SC [17]. We also predict and confirm an isotope effect in ρ s induced by impurity scattering. The isotope effects in T c and ρ s are mapped as a function of doping in La 2−x Sr x Cu 1−y Zn y O 4 and we observe a canonical pseudogap behavior as well as a huge an...

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“…More than ten years after the discovery of the high-T c cuprate superconductors by Bednorz and Müller [1], there have been no microscopic theories that can describe the physics of high-T c superconductors completely and unambiguously. Due to the high T c values and the earlier observation of a small oxygen-isotope effect in a 90 K cuprate superconductor YBa 2 Cu 3 O 7−y [2][3][4], many theorists believe that the electron-phonon interaction cannot be the origin of high-T c superconductivity. Most physicists have thus turned their minds towards an alternative pairing interaction of purely electronic origin (e.g., see Ref.…”

Section: Introductionmentioning

confidence: 99%

Unconventional isotope effects in the high-temperature cuprate superconductors

Zhao

Keller

Conder

2001

J. Phys.: Condens. Matter

139

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We review various isotope effects in the high-Tc cuprate superconductors to assess the role of the electron-phonon interaction in the basic physics of these materials. Of particular interest are the unconventional isotope effects on the supercarrier mass, on the charge-stripe formation temperature, on the pseudogap formation temperature, on the EPR linewidth, on the spin-glass freezing temperature, and on the antiferromagnetic ordering temperature. The observed unconventional isotope effects strongly suggest that lattice vibrations play an important role in the microscopic pairing mechanism of high-temperature superconductivity.

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Isotope Effect in the High-TcSuperconductorsBa2Y
B. Batlogg
¹
,
R. J. Cava
²
,
A. Jayaraman
³

et al.

Cited by 531 publications

References 26 publications

Unified picture of the oxygen isotope effect in cuprate superconductors

Unified picture of the oxygen isotope effect in cuprate superconductors

Isotope Effect in the Superfluid Density of High-Temperature Superconducting Cuprates: Stripes, Pseudogap, and Impurities

Unconventional isotope effects in the high-temperature cuprate superconductors

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Isotope Effect in the High-TcSuperconductorsBa2YB. Batlogg1, R. J. Cava2, A. Jayaraman3 et al.

Cited by 531 publications

References 26 publications

Unified picture of the oxygen isotope effect in cuprate superconductors

Unified picture of the oxygen isotope effect in cuprate superconductors

Isotope Effect in the Superfluid Density of High-Temperature Superconducting Cuprates: Stripes, Pseudogap, and Impurities

Unconventional isotope effects in the high-temperature cuprate superconductors

Contact Info

Product

Resources

About

Isotope Effect in the High-TcSuperconductorsBa2Y
B. Batlogg
¹
,
R. J. Cava
²
,
A. Jayaraman
³

et al.