Research Articles

Pairing Symmetry in Single-Layer Tetragonal Tl2Ba2CuOβ+δ Superconductors

Science  19 Jan 1996:
Vol. 271, Issue 5247, pp. 329-332
DOI: 10.1126/science.271.5247.329


A high-resolution scanning superconducting quantum interference device microscopy study of tetragonal single-layer Tl2Ba2CuOβ+δ films, deposited on tricrystal SrTiO3 substrates, demonstrates the effect of spontaneously generated half flux quanta. This observation shows that in addition to YBa2Cu3O7, the order parameter symmetry in Tl2Ba2CuOβ+δ is consistent with that of a dx2-y2 pair state. This result also rules out any bilayer or twinning effects and any pairing that is incompatible with the fourfold rotational symmetry as in the Tl2Ba2CuOβ+δ superconducting system.