Oxygen isotope effects in : evidence for polaronic charge carriers and their condensation

Zhao, Guangyao; Conder, K.; Keller, H.; Müller, K. A.

doi:10.1088/0953-8984/10/40/010

Cited by 82 publications

(185 citation statements)

References 51 publications

Supporting

Mentioning

158

Contrasting

Order By: Relevance

“…The small OIS observed in the optimally doped cuprates suggest that phonons might not be important in bringing about high temperature superconductivity. However, the doping dependence of the OIS has been extensively studied in different cuprate systems [17,[20][21][22][23][24][25][26][27]. For a particular family of doped cuprates the OIS increases with decreasing T c , and can be even larger than the BCS value.…”

Section: Isotope Effect On the Superconducting Transition Temperamentioning

confidence: 99%

Unconventional isotope effects in the high-temperature cuprate superconductors

Zhao

Keller

Conder

2001

J. Phys.: Condens. Matter

Self Cite

139

View full text Add to dashboard Cite

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.

show abstract

Section: Isotope Effect On the Superconducting Transition Temperamentioning

confidence: 99%

Unconventional isotope effects in the high-temperature cuprate superconductors

Zhao

Keller

Conder

2001

J. Phys.: Condens. Matter

Self Cite

139

View full text Add to dashboard Cite

show abstract

“…On the other hand, there is overwhelming evidence that electron-phonon coupling is very strong in the cuprate superconductors [5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20] . In particular, various unconventional oxygen-isotope effects Zhao and his coworkers have observed since 1994 clearly indicate that the electron-phonon interactions are so strong that polarons/bipolarons are formed in doped cuprates [5][6][7][8][9]11,12,[14][15][16][17]19 and manganites 21,22 , in agreement with a theory of high-temperature superconductivity 23 and the original motivation for the discovery of high-temperature superconductivity 1 .…”

Section: Introductionmentioning

confidence: 99%

Pairing interactions and pairing mechanism in high-temperature copper oxide superconductors

Zhao

2005

Phys. Rev. B

Self Cite

View full text Add to dashboard Cite

The polaron binding energy Ep in undoped parent cuprates has been determined to be about 1.0 eV from the unconventional oxygen-isotope effect on the antiferromagnetic ordering temperature. The deduced value of Ep is in quantitative agreement with that estimated from independent optical data and that estimated theoretically from the measured dielectric constants. The substantial oxygenisotope effect on the in-plane supercarrier mass observed in optimally doped cuprates suggests that polarons are bound into the Cooper pairs. We also identify the phonon modes that are strongly coupled to conduction electrons from the angle-resolved photoemission spectroscopy, tunneling spectra, and optical data. We consistently show that there is a very strong electron-phonon coupling feature at a phonon energy of about 20 meV along the antinodal direction and that this coupling becomes weaker towards the diagonal direction. We further show that high-temperature superconductivity in cuprates is caused by strong electron-phonon coupling, polaronic effect, and significant coupling with 2 eV Cu-O charge transfer fluctuation.

show abstract

“…In the deeply underdoped regime, T c ∝ 1/m * * ab and 1/m * * ab ∝ J within the t − J model, so ∆T c /T c = ∆J/J = −(0.6 − 0.9)%, in disagreement with the measured values of −(5 − 12)% (Ref. [9]). Therefore, the t − J model cannot explain the doping dependence of the OIE on T c .…”

mentioning

confidence: 57%

Reply to Comment on ‘The pairing mechanism of high-temperature superconductivity: experimental constraints’

Zhao¹

2011

Phys. Scr.

Self Cite

View full text Add to dashboard Cite

In our recent paper entitled "Pairing mechanism of high-temperature superconductivity: Experimental constraints" (to be published in Physica Scripta), we review some crucial experiments that place strong constraints on the microscopic pairing mechanism of high-temperature superconductivity in cuprates. In particular, we show that phonons rather than spin-fluctuation play a predominant role in the microscopic pairing mechanism. We further show that the intrinsic pairing symmetry in the bulk is not d-wave, but extended s-wave (having eight line nodes) in hole-doped cuprates and nodeless s-wave in electron-doped cuprates. In contrast, the author of the Comment (to be published in Physica Scripta) argues that our conclusions are unconvincing and even misleading. In response to the criticisms in the Comment, we further show that our conclusions are well supported by experiments and his criticisms are lack of scientific ground.In our recent paper [1], we review some crucial experiments that place strong constraints on the microscopic pairing mechanism of high-temperature superconductivity in cuprates. In particular, we show that phonons rather than spin-fluctuation play a predominant role in the microscopic pairing mechanism. We further show that the intrinsic pairing symmetry in the bulk of cuprates is not d-wave, but extended s-wave (having eight line nodes) in hole-doped cuprates and nodeless s-wave in electron-doped cuprates. However, Plakida [2] has raised strong criticisms on these conclusions based on an oversimplified polaronic model and some experimental results that have been misinterpreted. Below we will show that our conclusions are well supported by experiments and the criticisms raised in the Comment are lack of scientific ground.In the Comment [2], the author first considers the oxygen-isotope effect (OIE) on T c by taking into account the observed oxygen-isotope effect on the in-plane effective supercarrier mass. He has used the weakcoupling BCS-like formula [Eq. (2) in the Comment] to calculate the doping dependence of the OIE on T c in La 2−x Sr x CuO 4−y (LSCO) on the assumption that the electron-phonon coupling constant λ ep has the same OIE on the in-plane effective supercarrier mass. Actually, Eq. (2) used in the Comment is incorrect. The correct T c formula in the (bi)polaron theory has the polaronic half bandwidth in front of the exponent rather than the phonon energy [3]. When the correct expression is applied, the theory describes well the doping dependence of the isotope exponents in many cuprate superconductors [3]. Also, the tunneling experiments [4,5] have consistently shown that λ ep is larger than 2.5 for optimally doped Bi 2 Sr 2 CaCu 2 O 8+y (BSCCO). Therefore, the weak-coupling BCS-like formula does not hold in cuprates. A strong-coupling formula has been used to consistently explain the negligible OIE on T c and substantial OIE on the in-plane effective supercarrier mass in nearly optimally doped BSCCO [6]. In the underdoped regime, superconductivity should be better described by th...

show abstract

Oxygen isotope effects in : evidence for polaronic charge carriers and their condensation

Cited by 82 publications

References 51 publications

Unconventional isotope effects in the high-temperature cuprate superconductors

Unconventional isotope effects in the high-temperature cuprate superconductors

Pairing interactions and pairing mechanism in high-temperature copper oxide superconductors

Reply to Comment on ‘The pairing mechanism of high-temperature superconductivity: experimental constraints’

Contact Info

Product

Resources

About