Superconducting Gap Anisotropy vs Doping Level in High-Tc Cuprates

Relation between the superconducting gap energy and the two-magnon raman peak energy in Bi(2)Sr(2)Ca(1-x)Y(x)Cu(2)O(8+delta)

The relation between the electronic excitation and the magnetic excitation for the superconductivity in Bi(2)Sr(2)Ca(1-x)Y(x)Cu(2)O(8+delta) was investigated by wide-energy Raman spectroscopy. In the underdoping region the B(1g) scattering intensity is depleted below the two-magnon peak energy due to the charge-spin interactions. The depleted region decreases according to the decrease of the two-magnon peak energy, as the carrier concentration increases. This two-magnon peak energy also determines the B(1g) superconducting gap energy as 2Delta approximately alphaPlanck's over 2piomega(two-magnon) approximately J(eff) (alpha = 0.34-0.41) from under to overdoping hole concentration.

Temperature Dependence of the Half-Integer Magnetic Flux Quantum

The temperature dependence of the half-integer magnetic flux quantum effect in thin-film tricrystal samples of the high-critical-temperature cuprate superconductor YBa(2)Cu(3)O(7-delta) was measured and found to persist from a temperature of 0.5 kelvin through a critical temperature of about 90 kelvin, with no change in total flux. This result implies that d-wave symmetry pairing predominates in this cuprate, with a small component of time-reversal symmetry breaking, if any, over the entire temperature range.