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arXiv · 2012.10272

Inhomogeneous superconductivity in LuxZr1-xB12 dodecaborides with dynamic charge stripes

A. Azarevich·A. Bogach·V. Glushkov·S. Demishev·A. Khoroshilov·K. Krasikov·V. Voronov·N. Shitsevalova·V. Filipov·S. Gabani·K. Flachbart·A. Kuznetsov·S. Gavrilkin·K. Mitsen·S. J. Blundell·N. Sluchanko
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Abstract

We have studied the normal and superconductive state characteristics (resistivity, Hall coefficient, heat capacity and magnetization) of model strongly correlated electronic systems LuxZr1-xB12 with cooperative Jahn-Teller instability of the boron rigid cage and with dynamic charge stripes. It was found that these metals are s-wave dirty limit superconductors with a small mean free path of charge carriers l = 5 - 140 A and with a Cooper pair size changing non-monotonously in the range 450 - 4000 A. The parent ZrB12 and LuB12 borides are type-I superconductors, and Zr to Lu substitution induces a type-I - type-II phase transition providing a variation of the Ginzburg-Landau-Maki parameter in the limits 0.65 < kappa1,2 < 6. We argue in favor of the two-band scenario of superconductivity in LuxZr1-xB12 with gap values Delta_1 ~ 14 K and Delta_2 ~ 6 - 8 K, with pairing corresponding to strong coupling limit (lambda_e-ph ~ 1) in the upper band, and to weak coupling (lambda_e-ph ~ 0.1 - 0.4) in the lower one. A pseudogap Delta_ps-gap ~ 60 - 110 K is observed in LuxZr1-xB12 above Tc. We discuss also the possibility of anisotropic single-band superconductivity with stripe-induced both pair-breaking and anisotropy, and analyze the origin of unique enhanced surface superconductivity detected in these model compounds.

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A. Azarevich, A. Bogach, V. Glushkov, S. Demishev, A. Khoroshilov, K. Krasikov, V. Voronov, N. Shitsevalova, V. Filipov, S. Gabani, K. Flachbart, A. Kuznetsov, S. Gavrilkin, K. Mitsen, S. J. Blundell, N. Sluchanko. 2020-12-18. Inhomogeneous superconductivity in LuxZr1-xB12 dodecaborides with dynamic charge stripes. https://doi.org/10.1103/physrevb.103.104515

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