Unconventional s -Wave Superconductivity in Fe(Se,Te)

Abstract

Breaking Convention The defining characteristics of a superconductor are symmetry of gap function, which tells us something about how pairs of electrons move through the sample, and the strength of that pairing. Together, this information gives us the highest temperature to which the superconductor can remain superconducting. In conventional superconductors the gap function is symmetric, or s-wave, and tends to have low transition temperatures. The newly discovered iron-based superconductors also have s -wave symmetry, but the rather high transition temperatures, in addition to other properties, indicate that they are not conventional. Hanaguri et al. (p. 474 ; see the Perspective by Hoffman ) use scanning tunneling microscopy to provide direct experimental confirmation of the unconventional s -wave pairing of the superconducting carriers in these materials.