Superconductivity in : On the double transition and multiband effects

Seyfarth, Gabriel; Brison, Jean-Pascal; Méasson, Marie-Aude; Braithwaite, D.; Lapertot, G.; Flouquet, J.

doi:10.1016/j.jmmm.2006.10.288

Cited by 4 publications

(2 citation statements)

References 18 publications

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“…The specific heat exhibits a very sharp peak at T c2 , suggesting a high quality of the crystal, but a rounded anomaly at T c1 . The consensus is that the higher temperature feature is related to inhomogeneous superconductivity [6,7,13,15], due to a distribution of T c s. This distribution can be the result of varying Pr stoichiometry. However, χ has a very sharp peak in low excitation fields at a specific temperature of 1.84 K (this temperature does not seem to be crystal-dependent either) suggesting a lack of a significant distribution of T c1 .…”

Section: Discussionmentioning

confidence: 99%

Superconductivity and disorder in PrOs₄Sb₁₂

McBriarty

Kumar

Stewart

et al. 2009

J. Phys.: Condens. Matter

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The specific heat, and dc and ac magnetic susceptibility are reported for a large single crystal of PrOs(4)Sb(12) and, after grinding, its powder. The physical properties of the crystal are typical of the majority of reported PrOs(4)Sb(12) samples. The room temperature effective paramagnetic moment of the crystal was consistent with the Pr(3+) ionic configuration and full (or nearly full) occupancy of the Pr sublattice. The crystal showed two distinct anomalies in the specific heat and an overall discontinuity in C/T of approximately 1000 mJ K(-2) mol(-1). The upper transition (at T(c1)) was characteristically rounded. The anomaly at T(c2) was very sharp, consistent with a good quality for the crystal. We observed a shoulder in χ(') and two peaks in χ('') below T(c1). However, there were no signatures in χ(') of the lower temperature transition. Grinding to powder size smaller than 50 µm completely suppresses the upper superconducting transition in both the specific heat and magnetic susceptibility. It also strongly reduces ΔC/T(c) at T(c2). Stress annealing brings back some of this lost ΔC/T(c) but does not restore the upper temperature transition. Possible explanations of the existence of two superconducting specific heat anomalies for single crystals are discussed.

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Section: Discussionmentioning

confidence: 99%

Superconductivity and disorder in PrOs₄Sb₁₂

McBriarty

Kumar

Stewart

et al. 2009

J. Phys.: Condens. Matter

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“…However, one should keep in mind that the coherence length was calculated from dH c2 /dT at T c , while H c2 versus T is strongly non-linear near T c in PrOs 4 Sb 12 . Very recently, Seyfarth [12] and collaborators observed a disappearance of the upper superconducting anomaly in the specific heat when a crystal was sliced to a platelet 50 µm thick. This thickness is comparable to the size of grains of our powdered sample.…”

Section: Discussionmentioning

confidence: 99%

On the nature of two superconducting transitions in the specific heat of PrOs$_4$Sb$_{12}$: Effects of crystal grinding

McBriarty,

Kumar,

Stewart

et al. 2007

Preprint

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Specific heat, dc-and ac-magnetic susceptibility are reported for a large single crystal of PrOs 4 Sb 12 and, after grinding, its powder. The room temperature effective paramagnetic moment of the crystal was consistent with the Pr 3+ ionic configuration and full occupancy of the Pr-sublattice. The crystal showed two distinct anomalies in the specific heat and an overall discontinuity in C/T of more than 1000 mJ/K 2 mol. The upper transition (at T c1 ) was rounded, in an agreement with previous reports. The anomaly at T c2 was very sharp, consistent with a good quality of the crystal. We observed a shoulder in χ' and two peaks in χ" below T c1 . However, there were no signatures in χ' of the lower temperature transition. PrOs 4 Sb 12 is extremely sensitive to grinding, which suppresses the upper superconducting transition in both the specific heat and magnetic susceptibility. ∆C/T c was reduced to 140 mJ/K 2 mol in the powdered sample. Existing data on ground, polished, and sliced crystals suggests the existence of a length scale of order 100 µ, characterizing the higher temperature superconducting phase.

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