- 作者: 丘應楠
- 作者服務機構: Dept. of Chemistry, Catholic Univ. of America, Washington, D.C., U.S.A.
- 中文摘要: A vibrationally coupled intervalent charge transfer theory is proposed for the copper oxide-superconductors. The proposed B/sub 1g/-vibrational distortion exactly interchanges the chemical environment of the neighboring copper atoms. A quadruple cell is constructed to accommodate the non-stoichiometry and a double copper-oxide-conducting chain with distorted symmetry is postulated. The distorted structure, prone to switching of the copper sites by vibration, is postulated to be the superconducting precursor. The leftover-oxygen, due to oxygen deficiency, is allowed to serve as a bridge between the chains and to oscillate with the vibration. Symmetry of the system, before and after distortion, is used to explain the spin-angular momentum change, needed to arrive at Cooper-paired electron/holes. The O/sup -/ and O/sup -2/ atoms are postulated to be the bridge for superexchange and charge flow between the(Cu/sup +1/)/(Cu/sup +3/) and (Cu/sup +1/)/(Cu/sup +2/) pairs. The same theory is used to interpret the mechanisms for the following three types of copper oxide-superconductors: YBa/sub 2/Cu/sub 3/O/sub 7-x/; La/sub 2-x/Sr/sub x/CuO/sub 4/ and the newly discovered electron superconductor Nd/sub 2-x/Ce/sub x/CuO/sub 4-y/. The bridge oxygen oscillation may be chosen not to come from the breathing mode but from the bending deformation mode that involves the relative motion of the Cu atoms (to the oxygen) giving rise to smaller oxygen isotope effect.
- 英文摘要: --
- 中文關鍵字: Superconductivity; High-T/Sub C/ Superconductors; Copper-Oxide Superconductors; Intervalent Charge Transfer; Oxygen Isotope Effect
- 英文關鍵字: 超導電性;超傳導性;高溫超導體;銅氧化物超導體;介電荷轉換;氧同位素效應