We report the electric transport and thermodynamic properties of the skutterudite-related La3Co4Sn13 and La3Rh4Sn13 superconductors. Applying an external pressure to La3Rh4Sn13, the resistive superconducting critical temperature Tc decreases, while the critical temperature of La3Co4Sn13 is enhanced with increasing pressure. The positive pressure coefficient dTc/dP correlates with a subtle structural transition in La3Co4Sn13 and is discussed in the context of lattice instabilities. Specific-heat data show that both compounds are typical BCS superconductors. However, La3Rh4Sn13 also exhibits a second superconducting phase at higher temperatures, which is characteristic of inhomogeneous superconductors. We calculate the specific heat for an inhomogeneous superconducting phase, which agrees well with experimental C(T) data for La3Rh4Sn13. We also found that an applied pressure reduces this second superconducting phase.
@article{arxiv.1403.6030,
title = {Superconductivity of La$_3$Co$_4$Sn$_{13}$ and La$_3$Rh$_4$Sn$_{13}$: A comparative study},
author = {A. Slebarski and M. Fijalkowski and M. M. Maska and M. Mierzejewski and B. D. White and M. B. Maple},
journal= {arXiv preprint arXiv:1403.6030},
year = {2014}
}