Elucidation of the specific-heat anomaly below T sub N in NpIr sub 2

Journal Article · Tue May 01 04:00:00 EDT 1990 · Physical Review, B: Condensed Matter; (USA)

DOI:https://doi.org/10.1103/PhysRevB.41.9336· OSTI ID:6884569

Stewart, G R; Andraka, B; Kim, J S ^[1]; Haire, R G ^[2]

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1. Department of Physics, University of Florida, Gainesville, Florida 32611 (USA)
2. Transuranium Research Laboratory, Chemistry Division, Oak Ridge National Laboratory, P.O. Box 2008, Oak Ridge, Tennessee 37831-6375 (USA)

The remarkable discontinuous change in the slope of the specific heat, with a resultant {gamma}{gt}400 mJ/mol K{sup 2} as {ital T}{r arrow}0, previously observed in the antiferromagnet NpIr{sub 2}, {ital T}{sub {ital N}}=6.7 K, has been investigated. The specific heat of a single-phase sample of NpIr{sub 2} in applied fields of 0, 5.5, and 11 T is reported along with the zero-field specific heat of NpIrOs, which has no magnetic transition in the specific heat down to the lowest temperature of measurement, 1.7 K. Instead, NpIrOs appears to be a new spin fluctuation system, {gamma}=376 mJ/mol K{sup 2}. Using the specific heat of NpIrOs as representing the nonmagnetic background contribution in NpIr{sub 2} appears to explain the sharp kink in {ital C} of NpIr{sub 2} below {ital T}{sub {ital N}} without having to invoke the existence of a third-order phase transition. Implications for spin fluctuations in magnetically ordered NpIr{sub 2} are discussed.

• DOE Contract Number: FG05-86ER45268
• OSTI ID: 6884569
• Journal Information: Physical Review, B: Condensed Matter; (USA), Journal Name: Physical Review, B: Condensed Matter; (USA) Vol. 41:13; ISSN PRBMD; ISSN 0163-1829
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360104* -- Metals & Alloys-- Physical Properties
ACTINIDE ALLOYS
ACTINIDE COMPOUNDS
ALLOYS
ANTIFERROMAGNETISM
CHALCOGENIDES
DATA
ELECTRONIC STRUCTURE
EXPERIMENTAL DATA
FLUCTUATIONS
INFORMATION
IRIDIUM ALLOYS
IRIDIUM COMPOUNDS
IRIDIUM OXIDES
KONDO EFFECT
MAGNETISM
NEEL TEMPERATURE
NEPTUNIUM ALLOYS
NEPTUNIUM COMPOUNDS
NEPTUNIUM OXIDES
NUMERICAL DATA
OXIDES
OXYGEN COMPOUNDS
PHYSICAL PROPERTIES
PLATINUM METAL ALLOYS
REFRACTORY METAL COMPOUNDS
SPECIFIC HEAT
THERMODYNAMIC PROPERTIES
TRANSITION ELEMENT COMPOUNDS
TRANSITION TEMPERATURE
TRANSURANIUM COMPOUNDS
ULTRALOW TEMPERATURE
VARIATIONS