Frustrated pentagonal Cairo lattice in the non-collinear antiferromagnet Bi4Fe5O13F

Artem M. Abakumov, Dmitry Batuk, Alexander A. Tsirlin, Clemens Prescher, Leonid Dubrovinsky, Denis V. Sheptyakov, Walter Schnelle, Joke Hadermann, Gustaaf Van Tendeloo

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20 Citations (Scopus)

Abstract

We report on the crystal structure and magnetism of the iron-based oxyfluoride Bi4Fe5O13F, a material prototype of the Cairo pentagonal spin lattice. The crystal structure of Bi 4Fe5O13F is determined by a combination of neutron diffraction, synchrotron x-ray diffraction, and transmission electron microscopy. It comprises layers of FeO6 octahedra and FeO4 tetrahedra forming deformed pentagonal units. The topology of these layers resembles a pentagonal least-perimeter tiling, which is known as the Cairo lattice. This topology gives rise to frustrated exchange couplings and underlies a sequence of magnetic transitions at T1=62 K, T2=71 K, and TN=178 K, as determined by thermodynamic measurements and neutron diffraction. Below T1, Bi4Fe5O13F forms a fully ordered non-collinear antiferromagnetic structure, whereas the magnetic state between T1 and TN may be partially disordered according to the sizable increase in the magnetic entropy at T 1 and T2. Bi4Fe5O13F reveals unanticipated magnetic transitions on the pentagonal Cairo spin lattice and calls for a further work on finite-temperature properties of this strongly frustrated spin model.

Original languageEnglish
Article number024423
JournalPhysical Review B - Condensed Matter and Materials Physics
Volume87
Issue number2
DOIs
Publication statusPublished - 30 Jan 2013
Externally publishedYes

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