Revisiting the magnetic and crystal structure of multiferroic KNiPO$_4$

Alexandre Pages; Jian-Rui Soh; Marjaneh Jafari Fesharaki; Henrik M. Ronnow; Hossein Ahmadvand

Revisiting the magnetic and crystal structure of multiferroic KNiPO$_4$

Strongly Correlated Electrons 2022-07-15 v1 Materials Science

Authors: Alexandre Pages , Jian-Rui Soh , Marjaneh Jafari Fesharaki , Henrik M. Ronnow , Hossein Ahmadvand

Abstract

The magnetic, dielectric and structural properties of type-I multiferroic KNiPO $_4$ have been investigated by neutron powder diffraction, magnetization, dielectric and high temperature synchrotron-XRD measurements. Below the N\'{e}el transition of $T_\mathrm{N}$ = 25 K, KNiPO $_4$ displays a weakly non-collinear antiferromagnetic (AFM) structure with the orientation of the Ni $^{2+}$ magnetic moments mainly along $a$ axis. The compound crystallizes in the polar orthorhombic $Pna2_1$ space group at room temperature. A second-order structural phase transition corresponding to the onset ferroelectricity is observed at around $T_\mathrm{C}\sim$ 594(3) $^\circ$ C, above which the crystal structure of KNiPO $_4$ adopts the centrosymmetric $Pnma$ space group. The compound also displays another structural phase transition at $T_\mathrm{0}\sim$ 469 -- 488 $^\circ$ C, with a first-order character, which is attributed to the rearrangement of oxygen ligands, resulting in a change in the nickel ion co-ordination from four to five.

Keywords

multiferroic KNiPO4 neutron powder diffraction antiferromagnetic structure structural phase transition ferroelectricity

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@article{arxiv.2207.06969,
  title  = {Revisiting the magnetic and crystal structure of multiferroic KNiPO$_4$},
  author = {Alexandre Pages and Jian-Rui Soh and Marjaneh Jafari Fesharaki and Henrik M. Ronnow and Hossein Ahmadvand},
  journal= {arXiv preprint arXiv:2207.06969},
  year   = {2022}
}

Revisiting the magnetic and crystal structure of multiferroic KNiPO$_4$

Abstract

Keywords

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