Itinerant antiferromagnetism in the nearly-heavy-fermion compound NpSn/sub 3/

Journal Article · Sat Mar 15 04:00:00 EST 1986 · Phys. Rev. B: Condens. Matter; (United States)

DOI:https://doi.org/10.1103/PhysRevB.33.3803· OSTI ID:6121830

Norman, M R; Koelling, D D

NpSn/sub 3/, with a paramagnetic electronic specific-heat coefficient ..gamma.., of 242 mJ/mol K/sup 2/, undergoes an antiferromagnetic phase transition at 9.5 K with a resultant drop in ..gamma.. to 88 mJ/mol K/sup 2/. This behavior of ..gamma.. (reduction by 64%) is typical of the ''heavier'' fermion antiferromagnets U/sub 2/Zn/sub 17/, UCd/sub 11/, and CePb/sub 3/. Self-consistent linear-augmented-plane-wave calculations within the local-density approximation have been performed for both phases to study this effect. The calculations include both spin-orbit and magnetic coupling on the same level throughout the self-consistency process. An electronic specific-heat coefficient of 102 mJ/mol K/sup 2/ is found for the paramagnetic phase: the largest value ever reported from a band-structure calculation. This large value implies that large enhancements observed in other heavy-fermion materials are not present in NpSn/sub 3/. A specific-heat coefficient of 39.7 mJ/mol K/sup 2/ was found for the antiferromagnetic phase, yielding a calculated 61% reduction in ..gamma.. as a consequence of undergoing the phase transition. A total moment of 0.21..mu../sub B/ was obtained (-0.18 spin, 0.39 orbital) indicating the itinerant nature of the magnetism. An analysis of the dramatic reduction in electronic specific heat through the transition, as well as the temperature dependence of C/T in the paramagnetic phase, is presented along with a discussion of the implications for the other heavy-fermion antiferromagnets.

• Research Organization: Materials Science and Technology Division, Argonne National Laboratory, Argonne, Illinois 60439
• DOE Contract Number: W-31109-ENG-38
• OSTI ID: 6121830
• Journal Information: Phys. Rev. B: Condens. Matter; (United States), Journal Name: Phys. Rev. B: Condens. Matter; (United States) Vol. 33:6; ISSN PRBMD
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360104* -- Metals & Alloys-- Physical Properties
ACTINIDE ALLOYS
ALLOYS
ANTIFERROMAGNETISM
ELECTRONIC SPECIFIC HEAT
INTERMETALLIC COMPOUNDS
JAHN-TELLER EFFECT
MAGNETISM
NEPTUNIUM ALLOYS
PARAMAGNETISM
PHASE TRANSFORMATIONS
PHYSICAL PROPERTIES
SPECIFIC HEAT
THERMODYNAMIC PROPERTIES
TIN ALLOYS