title: Critical exponents for isosymmetric phase transitions in BiFeO₃.
abstract: Recent studies of BiFeO(3) have revealed two first-order phase transitions that do not change symmetry (Pbnm-Pbnm at approx. 1200 K and Cc-Cc under uniaxial stress). Twenty years ago Ishibashi and Hidaka (1991 J. Phys. Soc. Japan 60 1634) showed that such systems generally exhibit a phase diagram with tricritical points and critical end points and gave the unusual mean-field critical exponents α = 2/3, β = 1/3 and γ = 2/3 at the end points. In the present paper I extend that to show δ = 3, ν = 1/3 and η = 0 and suggest some experimental tests.
authors.affiliation: Physics Department, Cavendish Laboratory, University of Cambridge, Cambridge CB3 0HE, UK.
authors.forename: J F
authors.initials: JF
authors.lastname: Scott
mesh_terms: D001729:Bismuth / Q000737:chemistry*; D005290:Ferric Compounds / Q000737:chemistry*; D008956:Models, Chemical; D044367:Phase Transition
chemical_list: D005290:Ferric Compounds; D001729:Bismuth