title: Pronounced enhancement of the lower critical field and critical current deep in the superconducting state of PrOs4Sb12.
abstract: We have observed an unexpected enhancement of the lower critical field H(c1)(T) and the critical current I(c)(T) deep in the superconducting state below T approximately 0.6 K (T/T(c) approximately 0.3) in the filled skutterudite heavy fermion superconductor PrOs(4)Sb(12). From a comparison of the behavior of H(c1)(T) with that of the heavy fermion superconductors U(1-x)Th(x)Be(13) and UPt(3), we speculate that the enhancement of H(c1)(T) and I(c)(T) in PrOs(4)Sb(12) reflects a transition into another superconducting phase that occurs below T/T(c) approximately 0.3. An examination of the literature reveals unexplained anomalies in other physical properties of PrOs(4)Sb(12) near T/T(c) approximately 0.3 that correlate with the features we have observed in H(c1)(T) and I(c)(T).
authors.affiliation: Max Planck Institute for Chemical Physics of Solids, Dresden, Germany.
authors.forename: T
authors.initials: T
authors.lastname: Cichorek
authors.forename: A C
authors.initials: AC
authors.lastname: Mota
authors.forename: F
authors.initials: F
authors.lastname: Steglich
authors.forename: N A
authors.initials: NA
authors.lastname: Frederick
authors.forename: W M
authors.initials: WM
authors.lastname: Yuhasz
authors.forename: M B
authors.initials: MB
authors.lastname: Maple