High-TcFerroelectricity Emerging from Magnetic Degeneracy in Cupric Oxide

Gianluca Giovannetti, Sanjeev Kumar, Alessandro Stroppa, Jeroen van den Brink, Silvia Picozzi, José Lorenzana
2011 Physical Review Letters  
Cupric oxide is multiferroic at unusual high temperatures. From density functional calculations we find that the low-T magnetic phase is paraelectric and the higher-T one ferroelectric, with a size and direction of polarization in good agreement with experiment. By mapping of the ab initio results on an effective spin model we find with Monte Carlo that in the high-T magnetic state non-collinearity and inversion symmetry breaking stabilize each other via the Dzyaloshinskii Moriya interaction.
more » ... riya interaction. This leads to a novel mechanism for multiferroicity, with the particular property that non-magnetic impurities enhance the effect.
doi:10.1103/physrevlett.106.026401 pmid:21405242 fatcat:q2saloijl5cutadbd5ibrmsfjy