UNIGE document Scientific Article
previous document  unige:33130  next document
add to browser collection
Title

Theory of the low-temperature phases in boracites: latent antiferromagnetism, weak ferromagnetism, and improper magnetostructural couplings
Authors
Toledano, Pierre
Schmid, Hans
Clin, Martial Guy Jean Marie
Rivera, Jean-Pierre
Published in Physical Review. B, Condensed Matter. 1985, vol. 32, no. 9, p. 6006-6038
Abstract A phenomenological theory of the magnetic and magnetoelectric properties of boracites is developed, using the Landau-Dzialoshinskii approach. An interpretation is proposed for the main distinctive features characterizing 11 members of this family of compounds. Three subclasses of materials are distinguished corresponding to 2 essentially different phys. situations. In Ni-I boracite the simultaneous ferromagnetic-ferroelectric-ferroelastic transition results from a nonlinear (improper) coupling of the magnetization, polarization, and strain components, to the primary order parameter identified as a "latent" antiferromagnetic ordering. Monoclinic Ni-I can be viewed as the 1st exptl. example of a new class of magnetic materials, which should be recognized macroscopically by an M .apprx. (Tc - T)3/2 variation law, the existence of a spontaneous structural ordering occurring simultaneously with the magnetic ordering, and a weak value of the magnetization despite its exchange origin. In the 2 other classes of trigonal and orthorhombic boracites, the transitions are purely magnetic, the order parameter having a 1- or 2-dimensional antiferromagnetic order, bilinearly coupled to a weak magnetization of relativistic origin. The dielectric and elastic anomalies, and the magnetoelectric properties in these 2 groups of boracites are explained by secondary couplings of the order parameter with the relevant nonspontaneous polar tensors. The complementarity of the 2 additional Landau-type approaches of structural and magnetic transitions is illustrated.
Keywords Structure magnetic boracite phys property — Magnetoelectric magnetism boracite theory
Identifiers
Full text
Article (Published version) (5.7 MB) - public document Free access
Other version: http://link.aps.org/doi/10.1103/PhysRevB.32.6006
Structures
Faculté des sciences / Section de chimie et biochimie / Département de chimie minérale, analytique et appliquée
Project FNS: 1984
Citation
(ISO format) 		TOLEDANO, Pierre et al. Theory of the low-temperature phases in boracites: latent antiferromagnetism, weak ferromagnetism, and improper magnetostructural couplings. In: Physical Review. B, Condensed Matter, 1985, vol. 32, n° 9, p. 6006-6038. https://archive-ouverte.unige.ch/unige:33130

234 hits

90 downloads

Contact an author

Update request

Update

Deposited on : 2014-01-10

Export document
Format :
Citation style :