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Title: Effect of pressure on the reentrant superconductor--normal-metal phase boundaries of the (La[sub 1[minus][ital n]]Ce[sub [ital n]])Al[sub 2] and (La[sub 1[minus][ital x]]Th[sub [ital x]])[sub 1[minus][ital n]]Ce[sub [ital n]] Kondo systems

Journal Article · · Physical Review, B: Condensed Matter; (United States)
; ;  [1];  [2];  [3]
  1. Department of Physics, Tufts University, Medford, Massachusetts 02155 (United States)
  2. Department of Physics and Astronomy, University of Kentucky, Lexington, Kentucky 40506 (United States)
  3. Department of Physics and Institute for Pure and Applied Physical Sciences, University of California, San Diego, La Jolla, California 92093 (United States)

Measurements of the superconducting critical temperature [ital T][sub [ital c]]([ital n],[ital P]) as a function of Ce concentration [ital n] and pressure [ital P][le]20 kbar are reported for the superconducting Kondo systems (La[sub 1[minus][ital n]]Ce[sub [ital n]])Al[sub 2] and (La[sub 1[minus][ital x]]Th[sub [ital x]])[sub 1[minus][ital n]]Ce[sub [ital n]] (0[le][ital x][le]0.25). Data for the (La[sub 1[minus][ital n]]Ce[sub [ital n]])Al[sub 2] system are partially consistent with the theory of Mueller-Hartmann and Zittartz (MHZ), assuming an increase of [ital T][sub [ital K]]/[ital T][sub [ital c]0] with [ital P], where [ital T][sub [ital K]] is the Kondo temperature and [ital T][sub [ital c]0] is the critical temperature of the pure host superconductor. However, the pressure evolution of the reentrant superconducting-normal phase boundaries for the (La[sub 0.8]Th[sub 0.2])[sub 1[minus][ital n]]Ce[sub [ital n]] system is unexpected, and inconsistent with the MHZ theory. We find no evidence for the existence of a third transition (predicted by MHZ) back to the superconducting state for either the (La[sub 0.8]Th[sub 0.2])[sub 1[minus][ital n]]Ce[sub [ital n]] or (La[sub 1[minus][ital n]]Ce[sub [ital n]])Al[sub 2] systems. Recent Monte Carlo calculations by Jarrell may explain our data for both alloy systems, provided strong electron-phonon coupling effects are taken into account, although the effects of interimpurity interactions on the data remain uncertain.

OSTI ID:
5294577
Journal Information:
Physical Review, B: Condensed Matter; (United States), Vol. 49:6; ISSN 0163-1829
Country of Publication:
United States
Language:
English