Critical behavior of a site-diluted three-dimensional Ising magnet

Journal Article · Wed Jun 01 04:00:00 EDT 1983 · Phys. Rev. B: Condens. Matter; (United States)

DOI:https://doi.org/10.1103/PhysRevB.27.6747· OSTI ID:5970037

Birgeneau, R J; Cowley, R A; Shirane, G; Yoshizawa, A H; Belanger, D P; King, A R; Jaccarino, V

The critical behavior of the site-diluted three-dimensional Ising antiferromagnet Fe/sub 1-x/Zn/sub x/F/sub 2/ has been studied with the use of neutron scattering and linear birefringence techniques. The neutron scattering measurements were performed on a crystal with xapprox. =0.5 and T/sub N/ = 42.50 K. The critical scattering has a Lorentzian profile both above and below T/sub N/. The staggered susceptibility and correlation length exhibit power-law divergences over the reduced-temperature range 10/sup -1/ to 2 x 10/sup -3/ with critical exponents ..gamma.. = ..gamma..' = 1.44 +- 0.06 and ..nu.. = ..nu..' = 0.73 +- 0.03, respectively. From the linear birefringence ..delta..n, the critical behavior of the magnetic heat capacity was determined on a crystal with x = 0.4 and T/sub N/ = 47.05 K. d(..delta..n)/dT clearly exhibits cusplike behavior rather than a power-law divergence over the reduced-temperature range 2 x 10/sup -2/ to 10/sup -3/ with exponent ..cap alpha.. = ..cap alpha..' = -0.09 +- 0.03. The correlation-length and heat-capacity critical indices satisfy the hyperscaling relation 3..nu..+..cap alpha..-2 = 0 to within the experimental errors. Since all measured exponents differ markedly from the pure Ising values, this strongly suggests that random-exchange Ising behavior has been observed. The results are consistent with recent theoretical predictions for the random-exchange Ising fixed point by Newman and Riedel.

• Research Organization: Brookhaven National Laboratory, Upton, New York 11978
• OSTI ID: 5970037
• Journal Information: Phys. Rev. B: Condens. Matter; (United States), Journal Name: Phys. Rev. B: Condens. Matter; (United States) Vol. 27:11; ISSN PRBMD
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360603* -- Materials-- Properties
ANTIFERROMAGNETIC MATERIALS
BIREFRINGENCE
CAPACITY
COHERENT SCATTERING
CRYSTAL MODELS
DIFFRACTION
FLUORIDES
FLUORINE COMPOUNDS
HALIDES
HALOGEN COMPOUNDS
IRON COMPOUNDS
IRON FLUORIDES
ISING MODEL
MAGNETIC MATERIALS
MAGNETIC PROPERTIES
MAGNETIC SUSCEPTIBILITY
MATERIALS
MATHEMATICAL MODELS
NEUTRON DIFFRACTION
PHASE TRANSFORMATIONS
PHYSICAL PROPERTIES
RANDOMNESS
REFRACTION
SCATTERING
SPECIFIC HEAT
THERMODYNAMIC PROPERTIES
TRANSITION ELEMENT COMPOUNDS
ZINC COMPOUNDS
ZINC FLUORIDES
ZINC HALIDES