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Title: Second Low-Temperature Phase Transition in Frustrated UNi{sub 4} B

Abstract

Hexagonal UNi{sub 4}B is magnetically frustrated, yet it orders antiferromagnetically at T{sub N}=20 K . However, one-third of the U spins remains paramagnetic below this temperature. In order to track these spins to lower temperature, we measured the specific heat C of UNi{sub 4}B between 100 mK and 2thinspthinspK, in applied fields up to 9 T. A sharp kink in C at T{sup *}{approx}330 mK is observed at zero field, which we interpret as an indication of a second phase transition involving paramagnetic U. We attribute the rise in {gamma}=C/T between 7 K and 330 mK and the absence of a large entropy liberated at T{sup *} to a combination of Kondo screening effects and frustration that strongly modifies the low T transition. {copyright} {ital 1999} {ital The American Physical Society}

Authors:
;  [1]; ; ;  [2]
  1. Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)
  2. Kamerling Onnes Laboratory, Leiden University, P.O. Box 9504, 2300 RA Leiden (The Netherlands)
Publication Date:
OSTI Identifier:
686474
Resource Type:
Journal Article
Journal Name:
Physical Review Letters
Additional Journal Information:
Journal Volume: 83; Journal Issue: 10; Other Information: PBD: Sep 1999
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; URANIUM BORIDES; NICKEL BORIDES; PHASE TRANSFORMATIONS; ANTIFERROMAGNETIC MATERIALS; TEMPERATURE DEPENDENCE; SPECIFIC HEAT; KONDO EFFECT; INTERMETALLIC COMPOUNDS

Citation Formats

Movshovich, R., Jaime, M., Mentink, S., Menovsky, A.A., and Mydosh, J.A. Second Low-Temperature Phase Transition in Frustrated UNi{sub 4} B. United States: N. p., 1999. Web. doi:10.1103/PhysRevLett.83.2065.
Movshovich, R., Jaime, M., Mentink, S., Menovsky, A.A., & Mydosh, J.A. Second Low-Temperature Phase Transition in Frustrated UNi{sub 4} B. United States. doi:10.1103/PhysRevLett.83.2065.
Movshovich, R., Jaime, M., Mentink, S., Menovsky, A.A., and Mydosh, J.A. Wed . "Second Low-Temperature Phase Transition in Frustrated UNi{sub 4} B". United States. doi:10.1103/PhysRevLett.83.2065.
@article{osti_686474,
title = {Second Low-Temperature Phase Transition in Frustrated UNi{sub 4} B},
author = {Movshovich, R. and Jaime, M. and Mentink, S. and Menovsky, A.A. and Mydosh, J.A.},
abstractNote = {Hexagonal UNi{sub 4}B is magnetically frustrated, yet it orders antiferromagnetically at T{sub N}=20 K . However, one-third of the U spins remains paramagnetic below this temperature. In order to track these spins to lower temperature, we measured the specific heat C of UNi{sub 4}B between 100 mK and 2thinspthinspK, in applied fields up to 9 T. A sharp kink in C at T{sup *}{approx}330 mK is observed at zero field, which we interpret as an indication of a second phase transition involving paramagnetic U. We attribute the rise in {gamma}=C/T between 7 K and 330 mK and the absence of a large entropy liberated at T{sup *} to a combination of Kondo screening effects and frustration that strongly modifies the low T transition. {copyright} {ital 1999} {ital The American Physical Society}},
doi = {10.1103/PhysRevLett.83.2065},
journal = {Physical Review Letters},
number = 10,
volume = 83,
place = {United States},
year = {1999},
month = {9}
}