paper

Camelback-shaped band reconciles heavy electron behavior with weak electronic Coulomb correlations in superconducting TlNi2Se2

arXiv:1412.7016 · doi:10.1103/PhysRevB.92.081116

Abstract

Using high-resolution photoemission spectroscopy and first-principles calculations, we characterize superconducting TlNi $_{2}$ Se $_{2}$ as a material with weak electronic Coulomb correlations leading to a bandwidth renormalization of 1.4. We identify a camelback-shaped band, whose energetic position strongly depends on the selenium height. While this feature is universal in transition metal pnictides, in TlNi $_{2}$ Se $_{2}$ it lies in the immediate vicinity of the Fermi level, giving rise to a pronounced van Hove singularity. The resulting heavy band mass resolves the apparent puzzle of a large normal-state specific heat coefficient (Phys. Rev. Lett. 112, 207001) in this weakly correlated compound.

5 pages, 4 figures