Phase transitions in an Ising model for monolayers of coadsorbed atoms

Journal Article · Mon Oct 01 04:00:00 EDT 1979 · Phys. Rev., B: Condens. Matter; (United States)

DOI:https://doi.org/10.1103/PhysRevB.20.2893· OSTI ID:5854882

Lee, H H; Landau, D P

A Monte Carlo method is used to study a simple S=1 Ising (lattice-gas) model appropriate for monolayers composed of two kinds of atoms on cubic metal substrates H = K/sub nn/ ..sigma../sub nn/ S/sup 2//sub i/zS/sup 2//sub j/z + J/sub nnn/ ..sigma../sub nnn/ S/sub i/zS/sub j/z + ..delta.. ..sigma../sub i/ S/sup 2//sub i/z (where nn denotes nearest-neighbor and nnn next-nearest-neighbor pairs). The phase diagram is determined over a wide range of ..delta.. and T for K/sub nn//J/sub nnn/=1/4. For small (or negative) ..delta.. we find an antiferromagnetic 2 x 1 ordered phase separated from the disordered state by a line of second-order phase transitions. The 2 x 1 phase is separated by a line of first-order transitions from a c (2 x 2) phase which appears for larger ..delta... The 2 x 1 and c (2 x 2) phases become simultaneously critical at a bicritical point and the phase boundary of the c (2 x 2) ..-->.. disordered transition shows a tricritical point.

• Research Organization: Department of Physics and Astronomy, University of Georgia, Athens, Georgia 30602
• OSTI ID: 5854882
• Journal Information: Phys. Rev., B: Condens. Matter; (United States), Journal Name: Phys. Rev., B: Condens. Matter; (United States) Vol. 20:7; ISSN PRBMD
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360102* -- Metals & Alloys-- Structure & Phase Studies
ADSORPTION
CARBON COMPOUNDS
CARBON MONOXIDE
CARBON OXIDES
CHALCOGENIDES
CRYSTAL LATTICES
CRYSTAL MODELS
CRYSTAL STRUCTURE
CRYSTAL-PHASE TRANSFORMATIONS
CUBIC LATTICES
DIAGRAMS
DISSOCIATION
ELEMENTS
IRON
ISING MODEL
MATHEMATICAL MODELS
METALS
MOLYBDENUM
MONTE CARLO METHOD
OXIDES
OXYGEN COMPOUNDS
PHASE DIAGRAMS
PHASE TRANSFORMATIONS
REFRACTORY METALS
SORPTION
SUBSTRATES
TRANSITION ELEMENTS
TUNGSTEN
TWO-DIMENSIONAL CALCULATIONS