High temperature superconductors might be vibrational

High temperature superconductors might be vibrational after all, at least in part. Low temperature (4 K) superconductors operate according to the Bardeen-Cooper-Schrieffer (BCS) viewpoint. Electrons pair up and enter into a single unified quantum state through the agency of vibrations of the underlying lattice of atoms, an occurrence which can also be described in terms of the exchange of phonons. This BCS mechanism is inherently fragile and not expected to survive in the warmer, 100-K, regime where high temperature superconductors operate.

Therefore new tests conducted at SLAC's Stanford Synchrotron Radiation Laboratory (SSRL) and LBL's Advanced Light Source (ALS) came as a surprise. Researchers shot carefully selected photons into various cuprate superconductor samples and observed a kink in the energy spectrum of the ejected electrons, a kink which they associate with an underlying electron-phonon resonance, suggesting some kind of BCS behavior at work. (Lanzara et al., Nature, 2 August 2001.)