Monte Carlo studies of an fcc Ising antiferromagnetwith nearest- and next-nearest-neighbor interactions

Journal Article · Thu May 01 04:00:00 EDT 1980 · Phys. Rev., B: Condens. Matter; (United States)

DOI:https://doi.org/10.1103/PhysRevB.21.4027· OSTI ID:5478955

Phani, M K; Lebowitz, J L; Kalos, M H

We have investigated, via Monte Carlo computations, the phase diagram of an ordering binary alloy: equivalent to an Ising spin system: on an fcc lattice with nearest- and next-nearest-neighbor pair interactions H=J summation/sub nn/ sigma/sub i/sigma/sub j/-..cap alpha..J summation/sub nnn/ sigma/sub i/sigma/sub j/, sigma/sub i/= +- 1, J>0. Our studies indicate that this system undergoes a first-order transition: i.e., there is a discontinuity in the energy and order parameters as a function of temperature, for values -1< or approx. =..cap alpha..< or approx. =0.25. For larger values of vertical-bar..cap alpha..vertical-bar the transition appears to be continuous, without any metastable states. Our results are in good agreement with Kikuchi's cluster variation method at the two values of ..cap alpha.. at which it has been applied, namely, 0 and -0.25. For ..cap alpha..< or approx. =-0.5 renormalization-group arguments strongly indicate that the transition is first order. If this is so, then our results indicate that the discontinuities for ..cap alpha..<-1 must be very small. The nature of the ground states changes at ..cap alpha..=0 and -0.5. At these values of ..cap alpha.. the ground states are infinitely degenerate. The structure of the low-temperature phases, at all values of ..cap alpha.., is discussed.

• Research Organization: Departments of Mathematics and Physics, Rutgers University, New Brunswick, New Jersey 08903
• DOE Contract Number: EY-76-C-02-3077
• OSTI ID: 5478955
• Journal Information: Phys. Rev., B: Condens. Matter; (United States), Journal Name: Phys. Rev., B: Condens. Matter; (United States) Vol. 21:9; ISSN PRBMD
• Country of Publication: United States
• Language: English

Related Subjects

656000* -- Condensed Matter Physics
75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
ALLOY SYSTEMS
ANTIFERROMAGNETISM
BINARY ALLOY SYSTEMS
CRYSTAL LATTICES
CRYSTAL MODELS
CRYSTAL STRUCTURE
CUBIC LATTICES
DIAGRAMS
ENERGY LEVELS
FCC LATTICES
GROUND STATES
ISING MODEL
MAGNETISM
MATHEMATICAL MODELS
ORDER PARAMETERS
ORDER-DISORDER TRANSFORMATIONS
PHASE DIAGRAMS
PHASE TRANSFORMATIONS
TEMPERATURE DEPENDENCE