D. Varshney et al., Superconductivity and normal state in-plane resistivity of electron-doped cuprates Nd-Ce-CuO: screened optical-phonon approach, SUPERCOND S, 13(9), 2000, pp. 1345-1355
We have evolved an effective two-dimensional dynamic interaction, which emb
odies the screening of electrons by optical phonons and by plasmons to conf
er the attributes of the pairing mechanism leading to superconductivity in
layered electron-doped cuprates. The electron-doped Nd-Ce-CuO cuprate behav
es as an ionic solid containing isolated CuO2 layers of electrons as carrie
rs, and a model dielectric function is set up that fulfils the appropriate
sum rules on the electronic and ionic polarizabilities. Following strong co
upling theory, the superconducting transition temperature of optimally-dope
d Nd-Ce-CuO is estimated as 28 K and the energy gap ratio is larger than th
e Bardeen-Cooper-Schrieffer value. The isotope effect exponent, coherence l
ength and magnetic penetration depth are also estimated. Ziman's formula of
resistivity is employed for analysis and a comparison is made with the tem
perature-dependent resistivity of a single crystal. The estimated phonon co
ntribution together with the residual resistivity is lower than the reporte
d data. The subtracted data infers a clear quadratic temperature dependence
from T-c to near to room temperature. The implications of the model and it
s analysis are discussed.