NMR study of high- Tc superconductors

• Published in: Physica. B, Condensed matter Vol. 223; pp. 478 - 483
• Main Authors: Asayama, K, Kitaoka, Y, Zheng, G.-q, Ishida, K, Magishi, K
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 02-06-1996
• ISSN: 0921-4526; 1873-2135
• DOI: 10.1016/0921-4526(96)00153-6

Recent NMR study of high-
T
c superconductors carried out by Osaka group is reviewed.
NQR frequency
v
Q
, Knight shift
K, T
1 of
63Cu and
17O were measured over a wide hole doping range from light- to heavy-doped systems, LSCO, YBCO, HBCCO, BSCCO, TBCCO and TBCO, together with impurity and pressure effect. By analysing
v
Q
,
K and
T
1, the local hole numbers of Cu and O at the CuO
2 plane,
n(Cu) and
n(O) the relative magnitude of the uniform susceptibility,
χ
0 and the low-frequency component of the antiferromagnetic spin fluctuations (AFSF),
χ
Q
/
Γ (
χ
Q
is the staggered susceptibility and Γ is the characteristic energy of the spin fluctuation at
q = 0) are obtained. The relation between
n(Cu)
n(O) and
χ
Q
,
χ
Q
/
Γ,
Γ
C etc. were discussed. There are optimum values of
n(Cu)/2
n(O) and
n(Cu) + 2
n(O) to give maximum
T
C. The NMR results in the superconducting state are well-explained by d-wave pairing model. The result is consistent with the AFSF mediated superconducting model.