Superconductivity without nesting in LiFeAs

Phys Rev Lett. 2010 Aug 6;105(6):067002. doi: 10.1103/PhysRevLett.105.067002. Epub 2010 Aug 2.

Abstract

We have studied the electronic structure of the nonmagnetic LiFeAs (T(c)∼18 K) superconductor using angle-resolved photoemission spectroscopy. We find a notable absence of the Fermi surface nesting, strong renormalization of the conduction bands by a factor of 3, high density of states at the Fermi level caused by a van Hove singularity, and no evidence for either a static or a fluctuating order except superconductivity with in-plane isotropic energy gaps. Our observations suggest that these electronic properties capture the majority of ingredients necessary for the superconductivity in iron pnictides.