Spin-glass behavior of A Fe sub 4 Al sub 8 ( A =Th,U,Np) intermetallics

Journal Article · Wed Oct 31 23:00:00 EST 1990 · Physical Review, B: Condensed Matter; (USA)

DOI:https://doi.org/10.1103/PhysRevB.42.8507· OSTI ID:6003774

Gal, J ^[1]; Yaar, I; Regev, D; Fredo, S; Shani, G; Arbaboff, E ^[2]; Potzel, W; Aggarwal, K; Pereda, J A; Kalvius, G M ^[3]; Litterst, F J ^[4]; Schaefer, W; Will, G ^[5]

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1. Nuclear Engineering Department, Ben-Gurion-University of the Negev, 84105 Beer Sheva (Israel) Nuclear Research Center, 84190 Beer-Sheva (Israel) Physik Department E15, Technische Universitaet Muenchen, D-8046 Garchingbei Muenchen (West Germany)
2. Nuclear Engineering Department, Ben-Gurion-University of the Negev, 84105 Beer Sheva (Israel) Nuclear Research Center, 84190 Beer-Sheva (Israel)
3. Physik Department E15, Technische Universitaet Muenchen, D-8046 Garching bei Muenchen (West Germany)
4. Institut fuer Metallphysik, Technische Universitaet Braunschweig, D-3000 Braunschweig (West Germany) Physik Department E15, Technische Universitaet Muenchen, D-8046 Garching bei Muenchen (West Germany)
5. Mineralogisches Institut der Universitaet Bonn, D-5300 Bonn (West Germany) Kernforschonganlage, D-5170 Juelich (West Germany)

Combined ac- and dc-susceptibility, neutron-diffraction, and Moessbauer studies of UFe{sub 4}Al{sub 8}, NpFe{sub 4}Al{sub 8}, and ThFe{sub 4}Al{sub 8} argue for the establishment of a spin-glass (SG) state below {ital T}{sub SG}({ital B}{r arrow}0){approx}130, 120, and 110 K, respectively. The SG temperature {ital T}{sub SG}({ital B}) decreases with application of external magnetic field {ital B}. The ac susceptibility ({chi}{sub ac}) shows a sharp cusp at {ital T}{sub SG}({ital B}{approx}0). The isothermal and thermoremanent magnetization differ markedly and show temperature-dependent irreversibilities below {ital T}{sub SG}({ital B}). The Moessbauer spectra reveal onset of hyperfine splitting, indicating frozen spins below {ital T}{sub SG}(0). The neutron-diffraction studies of UFe{sub 4}Al{sub 8} and NpFe{sub 4}Al{sub 8} show that after switching off the external magnetic field greater than 3 T the U and Np momenta (2{ital a} site) are frozen parallel to the direction of the external field. We label the freezing temperature under high external fields {ital T}{sub OG}, and show that it serves as the upper limit of {ital T}{sub SG}({ital B}) with {ital T}{sub SG}({ital B}{r arrow}0){r arrow}{ital T}{sub OG}. For concentrated SG systems, {ital T}{sub SG}(0) is a reproducible value, independent of the observation time window, which indicates a true thermodynamic phase transition; the cusp in {chi}{sub ac}, however, is not necessarily a confirmation for the establishment of a SG state.

• OSTI ID: 6003774
• Journal Information: Physical Review, B: Condensed Matter; (USA), Journal Name: Physical Review, B: Condensed Matter; (USA) Vol. 42:13; ISSN PRBMD; ISSN 0163-1829
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360104* -- Metals & Alloys-- Physical Properties
ACTINIDE COMPOUNDS
ALLOYS
ALUMINIUM COMPOUNDS
INTERMETALLIC COMPOUNDS
IRON COMPOUNDS
MAGNETIC PROPERTIES
MAGNETIC SUSCEPTIBILITY
MOESSBAUER EFFECT
NEPTUNIUM COMPOUNDS
PHASE TRANSFORMATIONS
PHYSICAL PROPERTIES
SPIN GLASS STATE
THORIUM COMPOUNDS
TRANSITION ELEMENT COMPOUNDS
TRANSURANIUM COMPOUNDS
URANIUM COMPOUNDS