Eur. Phys. J. B 71, 355-360 (2009)
https://doi.org/10.1140/epjb/e2009-00223-3

Anisotropy of antiferromagnetic 180° domains in magnetoelectric LiMPO₄ (M = Fe, Co, Ni)

¹ HISKP, Universität Bonn, Nussallee 14-16, 53115 Bonn, Germany
² Department of Inorganic, Analytical and Applied Chemistry, University of Geneva, 30 quai Ernest-Anserment, 1211 Geneva 4, Switzerland
³ Ames Laboratory and Department of Physics and Astronomy, Iowa State University, Ames, IA, 50011, USA

Corresponding author: ^a zimmermann@hiskp.uni-bonn.de

Received: 14 March 2009
Revised: 24 May 2009
Published online: 30 June 2009

Abstract

An unusual variety of magnetic, magnetoelectric and ferrotoroidic properties was observed in the lithium-orthophosphates LiMPO₄ with M = Fe, Co, Ni by optical second harmonic generation. In spite of a largely similar magnetic and crystallographic structure the compounds exhibit pronounced differences in the topology of antiferromagnetic 180° domains. In LiCoPO₄ the antiferromagnetic domains coexist with ferrotoroidic, i.e., magnetic vortex domains. For LiNiPO₄ it was shown that the weak ferrimagnetic moment of the LiMPO₄ compounds along the spin direction is rigidly coupled to the AFM order parameter so that the sign of the magnetoelectric effect is reversed by a magnetic field only. Further effects of a static magnetic field on the system are discussed.