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arXiv · 1508.05224

Emergence of an incipient ordering mode in FeSe

Sahana Rößler·Cevriye Koz·Lin Jiao·Ulrich K. Rößler·Frank Steglich·Ulrich Schwarz·Steffen Wirth
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Abstract

The structurally simplest Fe-based superconductor FeSe with a critical temperature $T_{c}\approx$ 8.5 K displays a breaking of the four-fold rotational symmetry at a temperature $T_{s}\approx 87$ K. We investigated the electronic properties of FeSe using scanning tunneling microscopy/spectroscopy (STM/S), magnetization, and electrical transport measurements. The results indicated two new energy scales (i) $T^{*} \approx$ 75 K denoted by an onset of electron-hole asymmetry in STS, enhanced spin fluctuations, and increased positive magnetoresistance; (ii) $T^{**} \approx$ 22 - 30 K, marked by opening up of a partial gap of about 8 meV in STS and a recovery of Kohler's rule. Our results reveal onset of an incipient ordering mode at $T^{*}$ and its nucleation below $T^{**}$. The ordering mode observed here, both in spin as well as charge channels, suggests a coupling between the spins with charge, orbital or pocket degrees of freedom.

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Sahana Rößler, Cevriye Koz, Lin Jiao, Ulrich K. Rößler, Frank Steglich, Ulrich Schwarz, Steffen Wirth. 2015-08-21. Emergence of an incipient ordering mode in FeSe. https://doi.org/10.1103/physrevb.92.060505

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