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Title: Observation of low-lying levels in UBe{sub 13}

Abstract

Doping UBe{sub 13} with Th, La, Pr, or Ce destroys the as-yet not understood anomaly in the specific heat at 2 K. Using U{sub 0.97}Th{sub 0.03}Be{sub 13} as a background, we note that the anomaly in UBe{sub 13} fits very well with a Schottky temperature dependence, with fit parameters centered around a level splitting of 7 K but with only {similar_to}5% of the amplitude expected if all of the U ions participated. The decrease observed in the resistivity in UBe{sub 13} below 2 K is consistent with the freezing out of some type of degrees of freedom, which could also include magnetic scattering. Based on the known lack of magnetic-field dependence of the magnetization and the specific heat in the UBe{sub 13}, however, these low-lying {ital f} states cannot simply be understood as noncompensated magnetic moments as observed in, e.g., CeBe{sub 13}. We infer that this anomaly is intrinsic based on its behavior with annealing and improved purity, and on the fact that the entropy under this Schottky anomaly is shifted upon doping into more than a factor of 2 increase in the low-temperature {ital m}{sup *}({proportional_to}{gamma}) in U{sub 0.97}Th{sub 0.03}Be{sub 13}. The occurrence of a similar anomaly in anothermore » heavy-fermion superconductor, CeCu{sub 2}Si{sub 2}, makes the anomaly of some interest.« less

Authors:
;  [1]
  1. Department of Physics, University of Florida, Gainesville, Florida 32611-8440 (United States)
Publication Date:
OSTI Identifier:
55081
DOE Contract Number:  
FG05-86ER45268
Resource Type:
Journal Article
Journal Name:
Physical Review, B: Condensed Matter
Additional Journal Information:
Journal Volume: 51; Journal Issue: 22; Other Information: PBD: 1 Jun 1995
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; URANIUM ALLOYS; SPECIFIC HEAT; BERYLLIUM ALLOYS; INTERMETALLIC COMPOUNDS; TEMPERATURE DEPENDENCE; ELECTRIC CONDUCTIVITY; MAGNETIC FIELDS; MAGNETIZATION; MAGNETIC MOMENTS

Citation Formats

Kim, J S, and Stewart, G R. Observation of low-lying levels in UBe{sub 13}. United States: N. p., 1995. Web. doi:10.1103/PhysRevB.51.16190.
Kim, J S, & Stewart, G R. Observation of low-lying levels in UBe{sub 13}. United States. doi:10.1103/PhysRevB.51.16190.
Kim, J S, and Stewart, G R. Thu . "Observation of low-lying levels in UBe{sub 13}". United States. doi:10.1103/PhysRevB.51.16190.
@article{osti_55081,
title = {Observation of low-lying levels in UBe{sub 13}},
author = {Kim, J S and Stewart, G R},
abstractNote = {Doping UBe{sub 13} with Th, La, Pr, or Ce destroys the as-yet not understood anomaly in the specific heat at 2 K. Using U{sub 0.97}Th{sub 0.03}Be{sub 13} as a background, we note that the anomaly in UBe{sub 13} fits very well with a Schottky temperature dependence, with fit parameters centered around a level splitting of 7 K but with only {similar_to}5% of the amplitude expected if all of the U ions participated. The decrease observed in the resistivity in UBe{sub 13} below 2 K is consistent with the freezing out of some type of degrees of freedom, which could also include magnetic scattering. Based on the known lack of magnetic-field dependence of the magnetization and the specific heat in the UBe{sub 13}, however, these low-lying {ital f} states cannot simply be understood as noncompensated magnetic moments as observed in, e.g., CeBe{sub 13}. We infer that this anomaly is intrinsic based on its behavior with annealing and improved purity, and on the fact that the entropy under this Schottky anomaly is shifted upon doping into more than a factor of 2 increase in the low-temperature {ital m}{sup *}({proportional_to}{gamma}) in U{sub 0.97}Th{sub 0.03}Be{sub 13}. The occurrence of a similar anomaly in another heavy-fermion superconductor, CeCu{sub 2}Si{sub 2}, makes the anomaly of some interest.},
doi = {10.1103/PhysRevB.51.16190},
journal = {Physical Review, B: Condensed Matter},
number = 22,
volume = 51,
place = {United States},
year = {1995},
month = {6}
}