Experiments Probe the Wavefunction of Electron Pairs in High‐$Tc$ Superconductors Available to Purchase

One issue that has driven many of the experiments on high‐temperature superconductivity is the nature of the wavefunction of the electron pairs that carry the supercurrent (see PHYSICS TODAY, May 1993, page 17). For conventional superconductors, this wavefunction is isotropic, having an angular momentum $l = 0,$ that is, s‐wave. But for the anisotropic copper‐oxide materials that exhibit critical temperatures above 40 K, the wave‐function may not be so simple.