Regensburg 2013 – scientific programme

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TT: Fachverband Tiefe Temperaturen

TT 55: Correlated Electrons: Low-Dimensional Systems -Materials 2

TT 55.10: Talk

Thursday, March 14, 2013, 12:00–12:15, H21

Frustrated Cairo lattice in Bi₄Fe₅O₁₃F — •Alexander A. Tsirlin¹, Dmitry Batuk², and Artem M. Abakumov² — ¹National Institute for Chemical Physics and Biophysics, Tallinn, Estonia — ²EMAT, University of Antwerp, Belgium

Cairo lattice reveals an unusual topology of frustrated magnetic interactions that form pentagonal units. We present crystal structure and magnetism of Bi₄Fe₅O₁₃F, a recently discovered spin-5/2 compound, which is one of the few material prototypes of the Cairo spin lattice. Thermodynamic measurements reveal a sequence of phase transitions, with the onset of magnetic order at T_N=178 K and subsequent transformations at T₁=62 K and T₂=71 K. The low-temperature magnetic structure is non-collinear and commensurate, in agreement with theoretical expectations for the Cairo-lattice spin model. However, additional magnetic transitions below T_N have not been anticipated by theory. A comparative microscopic analysis of Bi₄Fe₅O₁₃F and the sister compound Bi₂Fe₄O₉ will be presented.

Financial support of the Mobilitas program of the ESF is acknowledged.