Physical properties of Lu 1− x Yb x Ni 2 B 2 C

Authors: Li, S.¹; De Andrade, M. C.¹; Freeman, E. J.¹; Sirvent, C.¹; Dickey, R. P.¹; Amann, A.¹; Frederick, N. A.¹; Rathnayaka, K. D. D.²; Naugle, D. G.²; Bud'ko, S. L.³; Canfield, P. C.³; Beyermann, W. P.⁴; Maple, M. B.¹

Source: Philosophical Magazine, Volume 86, Number 20, 11 July 2006 , pp. 3021-3041(21)

Publisher: Taylor and Francis Ltd

Abstract:

The Lu 1− x Yb x Ni 2 B 2 system exhibits superconductivity at low Yb concentrations (0≤ x ≤ 0.1), Kondo behaviour at low and moderate Yb concentrations (0≤ x ≤ 0.34), and heavy fermion behaviour with a non-magnetic ground state at high Yb concentrations. In order to characterize the evolution of these phenomena with x , we have performed dc magnetic susceptibility, electrical resistivity, thermoelectric power, and specific heat measurements on single crystals of Lu 1− x Yb x Ni 2 B 2 with various values of x between 0 and 1. The enhanced suppression of T c by Yb substitution, compared to other rare earth substitutions, is consistent with the behaviour of superconducting Kondo systems with T K ≫ T c when T K decreases with increasing x . The electronic specific heat coefficient γ increases from ∼11mJ/molK 2 for x =0 to ∼530mJ/molK 2 for x =1. The curve of the reduced specific heat jump Δ C /Δ C 0 versus T c / T c0 , where Δ C 0 and T c0 refer to the LuNi 2 B 2 C matrix, does not conform to the BCS theory, but is consistent with the magnetic pair breaking theory of Abrikosov and Gor'kov or the theory of Müller-Hartmann and Zittartz for superconductivity in the presence of the Kondo effect for . This is in agreement with the evolution of the upper critical field H c2 with x , where the slope decreases with increasing x .

Document Type: Research article

DOI: http://dx.doi.org/10.1080/14786430600651962

Affiliations: 1: Department of Physics and Institute for Pure and Applied Physical Sciences, University of California, San Diego, La Jolla, CA 92093 2: Department of Physics, Texas A&M University, College Station, TX 77843-4242 3: Ames Laboratory and Department of Physics, Iowa State University, Ames, IA 50011 4: Department of Physics, University of California, Riverside, CA 92521

Publication date: 2006-07-11

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• By this author: Li, S. ;  De Andrade, M. C. ;  Freeman, E. J. ;  Sirvent, C. ;  Dickey, R. P. ;  Amann, A. ;  Frederick, N. A. ;  Rathnayaka, K. D. D. ;  Naugle, D. G. ;  Bud'ko, S. L. ;  Canfield, P. C. ;  Beyermann, W. P. ;  Maple, M. B.

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