Magnetoelectric properties of LiCoPO4 and LiNiPO4
Abstract
In strong magnetic fields up to 20 T quasistatic measurements of the magnetic-field-induced electric polarization have been performed in LiNiPO4 single crystals between 4.2 and ~25 K. The magnetoelectric (ME) effect has been studied in detail near the Néel temperature. The temperature hysteresis of the polarization induced by a magnetic field was found. An anomalous temperature dependence of the magnetoelectric susceptibility during the phase transition and the ME ``butterfly loop'' were observed. The phenomenological theory of the magnetoelectric effect in LiCoPO4 and LiNiPO4 has been developed. A tentative explanation of the existence of the magnetoelectric ``butterfly loop'' is given. It is shown that there is a non-Lifshitz invariant in the free energy expansion which is linear in the spatial derivatives. Hence the phase transition to a space-modulated spin structure is possible. The influence of such a structure on the linear magnetoelectric effect is examined.
- Publication:
-
Physical Review B
- Pub Date:
- November 2000
- DOI:
- 10.1103/PhysRevB.62.12247
- Bibcode:
- 2000PhRvB..6212247K
- Keywords:
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- 75.50.Ee;
- Antiferromagnetics