Nodes in the gap structure of the iron-arsenide superconductor BaFe {1-x}Co x 2As 2 from c-axis heat transport measurements - Condensed Matter > SuperconductivityReport as inadecuate




Nodes in the gap structure of the iron-arsenide superconductor BaFe {1-x}Co x 2As 2 from c-axis heat transport measurements - Condensed Matter > Superconductivity - Download this document for free, or read online. Document in PDF available to download.

Abstract: The thermal conductivity k of the iron-arsenide superconductorBaFe {1-x}Co x 2As 2 was measured down to 50 mK for a heat current parallelk c and perpendicular k a to the tetragonal c axis, for seven Coconcentrations from underdoped to overdoped regions of the phase diagram 0.038< x < 0.127. A residual linear term k c0-T is observed in the T = 0 limit whenthe current is along the c axis, revealing the presence of nodes in the gap.Because the nodes appear as x moves away from the concentration of maximal T c,they must be accidental, not imposed by symmetry, and are therefore compatiblewith an s {+-} state, for example. The fact that the in-plane residual linearterm k a0-T is negligible at all x implies that the nodes are located inregions of the Fermi surface that contribute strongly to c-axis conduction andvery little to in-plane conduction. Application of a moderate magnetic fielde.g. H c2-4 excites quasiparticles that conduct heat along the a axis just aswell as the nodal quasiparticles conduct along the c axis. This shows that thegap must be very small but non-zero in regions of the Fermi surface whichcontribute significantly to in-plane conduction. These findings can beunderstood in terms of a strong k dependence of the gap Deltak which producesnodes on a Fermi surface sheet with pronounced c-axis dispersion and deepminima on the remaining, quasi-two-dimensional sheets.



Author: J.-Ph. Reid, M. A. Tanatar, X. G. Luo, H. Shakeripour, N. Doiron-Leyraud, N. Ni, S. L. Bud'ko, P. C. Canfield, R. Prozorov,

Source: https://arxiv.org/







Related documents