Unusual Nernst effect and spin density wave precursors in superconducting $\rm\bf LaFeAsO_{1-x}F_x$

Agnieszka Kondrat; Günter Behr; Bernd Büchner; Christian Hess

doi:10.1103/physrevb.83.092507

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arXiv · 1006.0715

Unusual Nernst effect and spin density wave precursors in superconducting $\rm\bf LaFeAsO_{1-x}F_x$

Agnieszka Kondrat·Günter Behr·Bernd Büchner·Christian Hess

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Abstract

The Nernst effect has recently proven as a sensitive probe for detecting unusual normal state properties of unconventional superconductors. Here we present a systematic study of the Nernst effect of the iron pnictide superconductor \laf with a particular focus on its evolution upon doping. For the parent compound we observe a huge negative Nernst coefficient accompanied with a severe violation of the Sondheimer cancellation in the spin density wave (SDW) ordered state. Surprisingly, an unusual and enhanced Nernst signal is also found at underdoping ($x=0.05$) despite the presence of bulk superconductivity and the absence of static magnetic order, strongly suggestive of SDW precursors at $T\lesssim150$ K. A more conventional normal state Nernst response is observed at optimal doping ($x=0.1$) where it is rather featureless with a more complete Sondheimer cancellation.

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Agnieszka Kondrat, Günter Behr, Bernd Büchner, Christian Hess. 2010-06-03. Unusual Nernst effect and spin density wave precursors in superconducting $\rm\bf LaFeAsO_{1-x}F_x$. https://doi.org/10.1103/physrevb.83.092507

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