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Oxygen-isotope Effects in Optimally-doped and Overdoped Bi 2Sr2CaCu2O8+Y: Understanding of the Microscopic Mechanism of High-temperature Superconductivity
Başlık:
Oxygen-isotope Effects in Optimally-doped and Overdoped Bi 2Sr2CaCu2O8+Y: Understanding of the Microscopic Mechanism of High-temperature Superconductivity
Yazar:
Khodagulyan, Armond, author.
ISBN:
9780438070431
Yazar Ek Girişi:
Fiziksel Tanımlama:
1 electronic resource (64 pages)
Genel Not:
Source: Masters Abstracts International, Volume: 57-06M(E).
Advisors: Guo-Meng Zhao Committee members: Oscar Bernal; Radi Jishi; Jose Rodriguez.
Özet:
Over the past 32 years one of the great mysteries in condensed matter physics has been the microscopic mechanism responsible for the pairing potential of the Cooper pairs in cuprate superconductors, which lose electrical resistance at rather high temperatures. Since the discovery of the cuprate superconductors by Bednorz and Muller in 1986's, the materials have been studied thoroughly, yet the mechanism behind what binds the electrons remains elusive. For most low temperature superconductors, the electron-phonon interaction is responsible for the formation of Cooper pairs, but for high temperature superconductors the mechanism remains puzzling. After years of extensive experimental and theoretical works, two competing mechanisms have been proposed for Cooper pair formation: magnetic interaction or strong electron-phonon interaction. This thesis details progress in understanding the cuprate problem through the oxygen-isotope experiments in optimally-doped and overdoped double-layer Bi2Sr2CaCu 2O8+y (BSCCO) superconductors.
Our oxygen-isotope effect experiments demonstrate that the oxygen-isotope exponent for optimally-doped BSCCO is 0.086, which is even larger than the value of 0.08 measured for the conventional phonon-mediated superconductor Nb3Sn. This suggests that the high-temperature superconductivity would be explained in terms of the conventional strong-coupling phonon mediated mechanism. As the doping level increases, the exponent decreases and crosses over to a negative value of -0.12 when Tc dropps to about 67 K in the heavily overdoped sample. Such an unusual doping dependence of the isotope exponent can be naturally explained in terms of the polaronic superconductivity theory, where polarons are bound into the Cooper pairs. The present work provides an essential insight into the microscopic pairing mechanism of high-temperature superconductivity.
Notlar:
School code: 0962
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Yer Numarası | Demirbaş Numarası | Shelf Location | Lokasyon / Statüsü / İade Tarihi |
---|---|---|---|
XX(692741.1) | 692741-1001 | Proquest E-Tez Koleksiyonu | Arıyor... |
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