The sign and profile of the thermal Hall conductivity κ xy gives important insights into the gap structure of multiband superconductors. With this perspective, we have investigated κ xy and the thermal conductivity κ xx in Ba 1-xK xFe 2As 2 which display large peak anomalies in the superconducting state. The anomalies imply that a large holelike quasiparticle (QP) population exists below the critical temperature T c. We show that the QP mean free path inferred from κ xx reproduces the observed anomaly in κ xy, providing a consistent estimate of a large QP population. Further, we demonstrate that the peak structure and holelike signal are consistent with a theoretical scenario where, despite potentially large gap variations on the electron pockets, the minimal homogeneous gap of the superconducting phase resides at a hole pocket. Implications for probing the gap structure in the broader class of pnictide superconductors are discussed.
|Original language||English (US)|
|Journal||Physical Review B - Condensed Matter and Materials Physics|
|State||Published - Nov 6 2012|
All Science Journal Classification (ASJC) codes
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics