PHYSICS SEMINAR
STUDY OF THE SEEBECK AND NERNST EFFECT IN
FeCrAs AND NbSe2
Paul Calvert
Physics Department,
Bishop's University
Tuesday, May 10, 2011
3:30 p.m.
Johnson 117D
The nature of high temperature superconductors could be better understood through the study of related materials. The Nernst and Seebeck coefficients were measured on a non-superconducting arsenide, FeCrAs, closely related to the iron-pnictides, and on the superconducting transition metal NbSe2. In FeCrAs the Seebeck coefficient was found to undergo a sign change in the vicinity of a known antiferromagnetic transition, possibly due to a Fermi surface reconstruction. The Nernst signal was nearly negligible but a slight deviation also suggested a reconstruction. The Nernst signal in NbSe2 was significant below a charge density wave transition and showed a curious field dependence that has been previously observed in the cuprate YBCO. The signatures of Fermi-surface reconstruction in the data suggest that these thermo-electric measurements could be applied to better understand the nature of phase transitions in non-conventional superconductors.
