Physics Department, Cavendish Laboratory, University of Cambridge, Cambridge CB3 0HE, UK.
J Phys Condens Matter. 2011 Jan 19;23(2):022202. doi: 10.1088/0953-8984/23/2/022202. Epub 2010 Dec 9.
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.
最近对 BiFeO(3) 的研究揭示了两个不改变对称性的一级相变（约 1200 K 时的 Pbnm-Pbnm 和单轴应力下的 Cc-Cc）。二十年前，Ishibashi 和 Hidaka（1991 J. Phys. Soc. Japan 60 1634）表明，这样的系统通常表现出具有三叉点和临界点的相图，并在临界点给出了不寻常的平均场临界指数 α = 2/3、β = 1/3 和 γ = 2/3。在本文中，我将其扩展到 δ = 3、ν = 1/3 和 η = 0，并提出了一些实验测试建议。
