Gap symmetry and charge density excitations in high-Tc superconductors with extended saddle points in electron spectrum

• Дата: 1999
• Автори: Pashitskii, E.A., Pentegov, V.I., Semenov, A.V.
• Формат: Стаття
• Мова: English
• Опубліковано: Інститут фізики конденсованих систем НАН України 1999
• Назва видання: Condensed Matter Physics
• Онлайн доступ: http://dspace.nbuv.gov.ua/handle/123456789/120526
• Назва журналу: Digital Library of Periodicals of National Academy of Sciences of Ukraine
• Цитувати: Gap symmetry and charge density excitations in high-Tc superconductors with extended saddle points in electron spectrum / E.A. Pashitskii, V.I. Pentegov, A.V. Semenov // Condensed Matter Physics. — 1999. — Т. 2, № 3(19). — С. 453-462. — Бібліогр.: 13 назв. — англ.

It is shown that the strong anisotropy of the one-particle electron spectrum, due to the presence of extended saddle-point features (ESPF) close to the Fermi level in the hole-type cuprates YBCO and BSCCO, leads to the occurrence of a low-frequency peak in the spectral function of the charge density fluctuations due to the presence of acoustic plasmon branch in the collective electron spectrum. The retarded anisotropic electron-plasmon interaction leads to the suppression of the static screened Coulomb repulsion for small transferred momenta and, consequently, to the effective attraction between electrons in the dx²-y²-wave channel of the Cooper pairing of current carriers. Breaking of C₄v symmetry in YBCO crystals leads to a possibility of a change of dx²-y²-wave symmetry of the gap to a mixed s − d gap symmetry for singlet Cooper pairs or to a p-wave gap symmetry for triplet pairs.