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.