Symmetry of Order Parameters in Multiband Superconductors LaRu4As12 and PrOs4Sb12 Probed by Local Magnetization Measurements

J. Juraszek, R. Wawryk, Z. Henkie, M. Konczykowski, and T. Cichorek
Phys. Rev. Lett. 124, 027001 – Published 16 January 2020
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Abstract

The temperature dependencies of the lower critical field Hc1(T) of several filled-skutterudite superconductors were investigated by local magnetization measurements. While LaOs4As12 and PrRu4As12 exhibit the Hc1(T) dependencies consistent with the single-band BCS prediction, for LaRu4As12 (the superconducting temperature Tc=10.4K) with a similar three-dimensional Fermi surface, we observe a sudden increase in Hc1(T) deep in a superconducting state below about 0.32Tc. Remarkably, a rapid rise of Hc1(T) at approximately the same reduced temperature 0.27Tc is also found for the heavy-fermion compound PrOs4Sb12 (Tc1.78K), in fair accord with the earlier macroscopic study. We attribute the unusual Hc1(T) dependencies of LaRu4As12 and PrOs4Sb12 to a kink structure in their superfluid densities due to different contributions from two nearly decoupled bands. Whereas LaRu4As12 is established as a two-band isotropic s-wave superconductor, nonsaturating behavior of Hc1(T) is observed for PrOs4Sb12, indicative of an anisotropic structure of a smaller gap. For this superconductor with broken time-reversal symmetry, our findings suggest a superconducting state with multiple symmetries of the order parameters.

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  • Received 4 June 2019
  • Revised 4 November 2019

DOI:https://doi.org/10.1103/PhysRevLett.124.027001

© 2020 American Physical Society

Physics Subject Headings (PhySH)

Condensed Matter, Materials & Applied Physics

Authors & Affiliations

J. Juraszek1, R. Wawryk1, Z. Henkie1, M. Konczykowski2, and T. Cichorek1

  • 1Institute of Low Temperature and Structure Research, Polish Academy of Sciences, 50-950 Wrocław, Poland
  • 2Laboratoire des Solides Irradiés, CEA/DRF/IRAMIS, École Polytechnique, CNRS, Institut Polytechnique de Paris, F-91128 Palaiseau, France

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Issue

Vol. 124, Iss. 2 — 17 January 2020

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