Abstract
We have measured the thermal conductivity of the iron pnictide superconductor LaFePO down to temperatures as low as mK and in magnetic fields up to 5 T. The data show a large residual contribution that is linear in temperature, consistent with the presence of low-energy electronic quasiparticles. We interpret the magnitude of the linear term, as well as the field and temperature dependence of thermal transport in several pairing scenarios. The presence of an unusual supralinear temperature dependence of the electronic thermal conductivity in zero magnetic field, and a high scattering rate with minimal suppression argues for a sign-changing nodal state.
- Received 23 September 2011
DOI:https://doi.org/10.1103/PhysRevB.85.014517
©2012 American Physical Society