Dipolar magnets and glasses: Neutron-scattering, dynamical, and calorimetric studies of randomly distributed Ising spins

Journal Article · Sat Sep 01 00:00:00 EDT 1990 · Physical Review, B: Condensed Matter; (USA)

DOI:https://doi.org/10.1103/PhysRevB.42.4631· OSTI ID:6384279

Reich, D H; Ellman, B; Yang, J; Rosenbaum, T F ^[1]; Aeppli, G ^[2]; Belanger, D P ^[3]

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1. University of Chicago, Chicago, IL (USA). James Franck Institute University of Chicago, Chicago, IL (USA). Department of Physics
2. AT T Bell Laboratories, Murray Hill, NJ (USA)
3. Physics Department, Brookhaven National Laboratory, Upton, NY (USA)

We have measured the magnetic correlations, susceptibility, specific heat, and thermal relaxation in the dipolar-coupled Ising system LiHo{sub {ital x}}Y{sub 1{minus}{ital x}}F{sub 4}. The material is ferromagnetic for spin concentrations at least as low as {ital x}=0.46, with a Curie temperature obeying mean-field scaling relative to that of pure LiHoF{sub 4}. In contrast, an {ital x}=0.167 sample behaves as a spin glass above its transition temperature, while an {ital x}=0.045 crystal shows very different glassy properties characterized by decreasing barriers to relaxation and nonexponential thermal relaxation as {ital T}{r arrow}0. We find the properties of the {ital x}=0.045 system to be consistent with a single low-degeneracy ground state with a large gap for excitations. The {ital x}=0.167 sample, however, supports a complex ground state with no appreciable gap, in accordance with prevailing theories of spin glasses. The underlying causes of such disparate behavior are discussed in terms of random clusters as probed by neutron studies of the {ital x}=0.167 sample.

• DOE Contract Number: AC02-76CH00016
• OSTI ID: 6384279
• Journal Information: Physical Review, B: Condensed Matter; (USA), Journal Name: Physical Review, B: Condensed Matter; (USA) Journal Issue: 7 Vol. 42:7; ISSN PRBMD; ISSN 0163-1829
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360603* -- Materials-- Properties
ALKALI METAL COMPOUNDS
COHERENT SCATTERING
CRYSTAL MODELS
DIFFRACTION
FERROMAGNETISM
FLUORIDES
FLUORINE COMPOUNDS
HALIDES
HALOGEN COMPOUNDS
HOLMIUM COMPOUNDS
HOLMIUM FLUORIDES
ISING MODEL
LITHIUM COMPOUNDS
LITHIUM FLUORIDES
LITHIUM HALIDES
MAGNETIC PROPERTIES
MAGNETIC SUSCEPTIBILITY
MAGNETISM
MATHEMATICAL MODELS
NEUTRON DIFFRACTION
PHYSICAL PROPERTIES
QUANTITY RATIO
RARE EARTH COMPOUNDS
RELAXATION
SCALING LAWS
SCATTERING
SPECIFIC HEAT
SPIN GLASS STATE
STOICHIOMETRY
TEMPERATURE DEPENDENCE
THERMODYNAMIC PROPERTIES
TRANSITION ELEMENT COMPOUNDS
YTTRIUM COMPOUNDS
YTTRIUM FLUORIDES