Point-contact Andreev reflection spectroscopy of heavy-fermion-metal/superconductor junctions

W. K. Park; H. Stalzer; J. L. Sarrao; J. D. Thompson; L. D. Pham; Z. Fisk; J. Frederick; P. C. Canfield; L. H. Greene

doi:10.1016/j.physb.2007.10.229

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arXiv · 0706.1376

Point-contact Andreev reflection spectroscopy of heavy-fermion-metal/superconductor junctions

W. K. Park·H. Stalzer·J. L. Sarrao·J. D. Thompson·L. D. Pham·Z. Fisk·J. Frederick·P. C. Canfield·L. H. Greene

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Abstract

Our previous point-contact Andreev reflection studies of the heavy-fermion superconductor CeCoIn$_5$ using Au tips have shown two clear features: reduced Andreev signal and asymmetric background conductance [1]. To explore their physical origins, we have extended our measurements to point-contact junctions between single crystalline heavy-fermion metals and superconducting Nb tips. Differential conductance spectra are taken on junctions with three heavy-fermion metals, CeCoIn$_5$, CeRhIn$_5$, and YbAl$_3$, each with different electron mass. In contrast with Au/CeCoIn$_5$ junctions, Andreev signal is not reduced and no dependence on effective mass is observed. A possible explanation based on a two-fluid picture for heavy fermions is proposed. [1] W. K. Park et al., Phys. Rev. B 72 052509 (2005); W. K. Park et al., Proc. SPIE-Int. Soc. Opt. Eng. 5932 59321Q (2005); W. K. Park et al., Physica C (in press) (cond-mat/0606535).

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W. K. Park, H. Stalzer, J. L. Sarrao, J. D. Thompson, L. D. Pham, Z. Fisk, J. Frederick, P. C. Canfield, L. H. Greene. 2007-06-10. Point-contact Andreev reflection spectroscopy of heavy-fermion-metal/superconductor junctions. https://doi.org/10.1016/j.physb.2007.10.229

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