Abstract
The phase diagram of U 1−x Th x Be 13 exhibits two irregular points at x C1=1.9 at.% and x C2=4.55 at.% which mark the endpoints of the concentration range where two phase transitions in specific heat measurements are observed. While it is clear that the upper one belongs to a superconducting phase transition, there are different interpretations for the lower one. It has been suggested that the lower transition involves magnetic correlations which coexist with a single superconducting state or that the lower transition separates two different superconducting states (one or both are probably non-s-wave like). In this scenario the onset of local magnetic order is discussed as being due to an accompanied antiferromagnetic transition or as a product of broken time reversal symmetry. To get more information about the nature of the two superconducting phases, substitution experiments with non-magnetic La and magnetic Gd on the U sites in U 0.97 Th 0.03 Be 13 were performed. From specific heat measurements we argue that the upper transition behaves with La/Gd doping like a conventional s-wave superconductor, whereas the lower transition cannot be brought in line with common pictures of superconducting transitions.
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REFERENCES
J. L. Smith, Z. Fisk, J. O. Willis, B. Batlogg, and H. R. Ott, J. Appl. Phys. 55, 1996 (1984).
P. Kumar and P. Wolfle, Phys. Rev. Lett. 59, 1954 (1987).
M. Sigrist and K. Ueda, Rev. Mod. Phys. 63, 239 (1991).
H. R. Ott, H. Rudigier, Z. Fisk, and J. L. Smith, Phys. Rev. B 31, 1651 (1985).
U. Rauchschwalbe, F. Steglich, G. R. Stewart, A. L. Giorgi, P. Fulde, and K. Maki, Europhys. Lett. 3, 751 (1987).
E. A. Knetch, J. A. Mydosh, R. H. Heffner, and J. L. Smith, Physica B 163, 209 (1990).
J. S. Kim, B. Andraka, and G. R. Stewart, Phys. Rev. B 44, 6921 (1991).
R. J. Zieve, D. S. Jin, T. F. Rosenbaum, J. S. Kim, and G. R. Stewart, Phys. Rev. Lett. 72, 756 (1994).
S. E. Lambert, Y. Dalichaouch, M. B. Maple, J. L. Smith, and Z. Fisk, Phys. Rev. Lett. 57, 1619 (1986).
B. Batlogg, B. Bishop, B. Golding, C. M. Varma, Z. Fisk, J. L. Smith, and H. R. Ott, Phys. Rev. Lett. 55, 1319 (1985).
R. H. Heffner, J. L. Smith, J. O. Willis, P. Birrer, C. Baines, F. N. Gygax, B. Hitti, E. Lippelt, H. R. Ott, A. Schenk, E. A. Knetch, J. A. Mydosh, and D. E. MacLaughlin, Phys. Rev. Lett. 65, 2816 (1990).
E. A. Knetch, G. J. Nieuwenhuys, J. A. Mydosh, R. H. Heffner, and J. L. Smith, Physica B 186–188, 251 (1993).
M. Sigrist and T. M. Rice, Phys. Rev. B 29, 2200 (1989).
J. S. Kim, B. Andraka, C. S. Jee, S. B. Roy, and G. R. Stewart, Phys. Rev. B 41, 11073 (1990).
R. Balian and N. R. Werthamer, Phys. Rev. 131, 1553 (1963).
G. R. Stewart, Rev. Sci. Instrum. 54, 1 (1983).
The δC1/γT C1 values are slightly smaller than the theoretical BCS-value 1.43, this, however, is also found for common BCS-superconductors like zinc with 1.25 and thallium with 1.15. E. A. Lynton, Superconductivity (1969), p. 148; J. Baedeen and J. R. Schrieffer, Recent Developments in Superconductivity, Progress in Low Temperature Physics, Vol. III, C. J. Gorter (ed.), Interscience, New York (1961), p. 212. A decrease of δC/γT C is anyway expected for magnetic impurities.
E.-W. Scheidt, T. Schreiner, J. S. Kim, and G. R. Stewart, accepted by Phys. Rev. B.
A. Abrikosov and L. P. Gorkov, Sov. Phys. JETP 12, 1234 (1961).
J. M. Lawrence, J. D. Thompson, and Y. Y. Chen, Phys. Rev. Lett. 54, 2537 (1985).
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Scheidt, EW., Schreiner, T. & Stewart, G.R. Influence of La and Gd Impurities on the Two Phase Transitions in U0.97Th0.03Be13 . Journal of Low Temperature Physics 114, 151–159 (1999). https://doi.org/10.1023/A:1021853920799
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DOI: https://doi.org/10.1023/A:1021853920799