Raman evidence for the superconducting gap and spin-phonon coupling in the superconductor Ca( Fe0.95Co0.05)(2)As-2

Kumar, Pradeep and Bera, Achintya and Muthu, DVS and Kumar, Anil and Waghmare, UV and Harnagea, L and Hess, C and Wurmehl, S and Singh, S and Buechner, B and Sood, AK (2011) Raman evidence for the superconducting gap and spin-phonon coupling in the superconductor Ca( Fe0.95Co0.05)(2)As-2. In: Journal of Physics: Condensed Matter, 23 (25).

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Abstract

Inelastic light scattering studies on a single crystal of electron-doped Ca(Fe0.95Co0.05)(2)As-2 superconductor, covering the tetragonal-to-orthorhombic structural transition as well as the magnetic transition at T-SM similar to 140 K and the superconducting transition temperature T-c similar to 23 K, reveal evidence for superconductivity-induced phonon renormalization. In particular, the phonon mode near 260 cm(-1) shows hardening below T-c, signaling its coupling with the superconducting gap. All three Raman active phonon modes show anomalous temperature dependence between room temperature and T-c, i.e. the phonon frequency decreases with lowering temperature. Further, the frequency of one of the modes shows a sudden change in temperature dependence at TSM. Using first-principles density functional theory based calculations, we show that the low temperature phase (T-c < T < T-SM) exhibits short-ranged stripe antiferromagnetic ordering, and estimate the spin-phonon couplings that are responsible for these phonon anomalies.

Item Type:	Journal Article
Publication:	Journal of Physics: Condensed Matter
Publisher:	IOP Publishing ltd
Additional Information:	Copyright of this article belongs to IOP Publishing ltd.
Department/Centre:	Division of Physical & Mathematical Sciences > Physics
Date Deposited:	29 Jun 2011 09:09
Last Modified:	29 Jun 2011 09:09
URI:	http://eprints.iisc.ac.in/id/eprint/38625

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