Displacive-type ferroelectricity from magnetic correlations within spin-chain.

Scientific reports

PubMedID: 25005869

Basu T, Kishore VV, Gohil S, Singh K, Mohapatra N, Bhattacharjee S, Gonde B, Lalla NP, Mahadevan P, Ghosh S, Sampathkumaran EV. Displacive-type ferroelectricity from magnetic correlations within spin-chain. Sci Rep. 2014;45636.
Observation of ferroelectricity among non-d(0) systems, which was believed for a long time an unrealistic concept, led to various proposals for the mechanisms to explain the same (i. e. magnetically induced ferroelectricity) during last decade. Here, we provide support for ferroelectricity of a displacive-type possibly involving magnetic ions due to short-range magnetic correlations within a spin-chain, through the demonstration of magnetoelectric coupling in a Haldane spin-chain compound Er2BaNiO5 well above its NĂ©el temperature of (TN = ) 32 K. There is a distinct evidence for electric polarization setting in near 60 K around which there is an evidence for short-range magnetic correlations from other experimental methods. Raman studies also establish a softening of phonon modes in the same temperature (T) range and T-dependent x-ray diffraction (XRD) patterns also reveal lattice parameters anomalies. Density-functional theory based calculations establish a displacive component (similar to d(0)-ness) as the root-cause of ferroelectricity from (magnetic) NiO6 chain, thereby offering a new route to search for similar materials near room temperature to enable applications.