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arXiv · 2204.12213

Nematic fluctuations mediated superconductivity revealed by anisotropic strain in Ba(Fe$_{1-x}$Co$_x$)$_2$As$_2$

J. -C. Philippe·A. Lespinas·J. Faria·A. Forget·D. Colson·S. Houver·M. Cazayous·A. Sacuto·I. Paul·Y. Gallais
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Abstract

Anisotropic strain is an external field capable of selectively addressing the role of nematic fluctuations in promoting superconductivity. We demonstrate this using polarization-resolved elasto-Raman scattering to probe the evolution of nematic fluctuations under strain in the normal and superconducting states of the paradigmatic iron-based superconductor Ba(Fe$_{1-x}$Co$_x$)$_2$As$_2$. In the non-superconducting parent compound BaFe$_2$As$_2$ we observe a strain-induced suppression of the nematic susceptibility which follows the expected behavior of an Ising order parameter under a symmetry breaking field. For the superconducting compound, the suppression of the nematic susceptibility correlates with the decrease of the superconducting critical temperature $T_c$. Our results indicate a significant contribution of nematic fluctuations to electron pairing and validate theoretical scenarios of enhanced $T_c$ near a nematic quantum critical point.

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J. -C. Philippe, A. Lespinas, J. Faria, A. Forget, D. Colson, S. Houver, M. Cazayous, A. Sacuto, I. Paul, Y. Gallais. 2022-04-26. Nematic fluctuations mediated superconductivity revealed by anisotropic strain in Ba(Fe$_{1-x}$Co$_x$)$_2$As$_2$. https://doi.org/10.1103/physrevlett.129.187002

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