Magnetic penetration depth in single crystals of SrPd2Ge2 superconductor

TitleMagnetic penetration depth in single crystals of SrPd2Ge2 superconductor
Publication TypeJournal Article
Year of Publication2013
AuthorsKim H, Sung NH, Cho BK, Tanatar MA, Prozorov R
Journal TitlePhysical Review B
Date Published03
Type of ArticleArticle
ISBN Number1098-0121
Accession NumberWOS:000316379100003
Keywordsdependence, field

The in-plane magnetic penetration depth lambda(m)(T) was measured in a single crystal of SrPd2Ge2 superconductor in a dilution refrigerator down to T = 60 mK and in magnetic fields up to H-dc = 1 T by using a tunnel diode resonator. The London penetration depth lambda saturates exponentially approaching T -> 0 indicating fully gapped superconductivity. The thermodynamic Rutgers formula was used to estimate lambda(0) = 426 +/- 60 nm which was used to calculate the superfluid density, rho(s)(T) = lambda(2)(0)/lambda(2)(T). Analysis of rho(s)(T) in the full temperature range shows that it is best described by a single-gap behavior, perhaps with somewhat stronger coupling. In a magnetic field, the measured penetration depth is given by the Campbell penetration depth which was used to calculate the theoretical critical current density j(c). For H <= 0.45 T, the strongest pinning is achieved not at the lowest, but at some intermediate temperature, probably due to matching effect between temperature-dependent coherence length and relevant pinning length scale. Finally, we find compelling evidence for surface superconductivity. Combining all measurements, the entire H-T phase diagram of SrPd2Ge2 is constructed with an estimated H-c2(0) = 0.4817 T. DOI: 10.1103/PhysRevB.87.094515

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