TY - JOUR
T1 - Bonds, bands, charge transfer excitations and superconductivity of YBa2Cu3O7-δ
AU - Yu, Jaejun
AU - Massidda, S.
AU - Freeman, A. J.
AU - Koeling, D. D.
N1 - Funding Information:
This work was supported by the National Science Foundation (DMR grant No. 85-20280) through the Northwestern University Materials Research Center and DMR grant No. 85-18607, and a computing grant from its Division for Advanced Scientific Computing and by the Department of Energy (Contract No. W-3!-109 ENG-38). We are grateful to NASA Ames personnel in the NAS program for help with the use of their CRAY2 and to C.L. Fu, K.R. Poeppelmeier, J. Redinger, and J.-H. Xu for helpful discussions.
PY - 1987/6/8
Y1 - 1987/6/8
N2 - The different energy dispersion and Fermi surfaces arising from the bands which dominate the electronic band structure near EF in YBa2Cu3O7-δ are presented and related to their orbital charge density distributions for the Cu2 plane and Cu1 chain arrangements thereby relating their physical and chemical descriptions. Magnetic isolation of the Y ions is found to explain the existence of high Tc superconductivity of the RBa2Cu3O7-δ compounds (where R = magnetic heavy lanthanides). A conventional phonon mechanism is found to be inadequate for obtaining high Tc. Charge transfer excitations ("excitons") of occupied Cu1-O dpπ bonding orbitals into their empty Cu1-O dpσ antibonding orbital partners result in poorly screened Cu3+-Cu4+-like charge fluctuations which induce attractive interactions (-U centers) both in the chains and to the 2D (Cu2) bands-thereby promoting the high Tc via exchange of these "excitons".
AB - The different energy dispersion and Fermi surfaces arising from the bands which dominate the electronic band structure near EF in YBa2Cu3O7-δ are presented and related to their orbital charge density distributions for the Cu2 plane and Cu1 chain arrangements thereby relating their physical and chemical descriptions. Magnetic isolation of the Y ions is found to explain the existence of high Tc superconductivity of the RBa2Cu3O7-δ compounds (where R = magnetic heavy lanthanides). A conventional phonon mechanism is found to be inadequate for obtaining high Tc. Charge transfer excitations ("excitons") of occupied Cu1-O dpπ bonding orbitals into their empty Cu1-O dpσ antibonding orbital partners result in poorly screened Cu3+-Cu4+-like charge fluctuations which induce attractive interactions (-U centers) both in the chains and to the 2D (Cu2) bands-thereby promoting the high Tc via exchange of these "excitons".
UR - http://www.scopus.com/inward/record.url?scp=0342829383&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=0342829383&partnerID=8YFLogxK
U2 - 10.1016/0375-9601(87)90807-3
DO - 10.1016/0375-9601(87)90807-3
M3 - Article
AN - SCOPUS:0342829383
VL - 122
SP - 203
EP - 208
JO - Physics Letters, Section A: General, Atomic and Solid State Physics
JF - Physics Letters, Section A: General, Atomic and Solid State Physics
SN - 0375-9601
IS - 3-4
ER -