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Magnetic Properties of (Fe1-xMnx)2AlB2 and the Impact of Substitution on the Magnetocaloric Effect

Published

Author(s)

D. Potashnikov, Elad Nisan NMN Caspi, A. Pesach, S. Kota, M. Sokol, L. A. Hanner, M. W. Barsoum, Hayden A Evans, A. Eyal, A. Keren, O. Rivin

Abstract

In this work, we investigate the magnetic structures of (Fe1−xMnx)2AlB2 solid-solution quaternaries in the x = 0 to 1 range using X-ray and neutron diffraction, magnetization measurements, and mean field theory calculations. While Fe2AlB2 and Mn2AlB2 are known to be ferromagnetic (FM) and antiferromagnetic (AFM), respectively, herein we focused on the magnetic structure of their solid solutions, which is not well understood. The FM ground state of Fe2AlB2 becomes a canted AFM at x {approximately equal} 0.2, with a monotonously diminishing FM component until x {approximately equal} 0.5. The FM transition temperature (TC) decreases linearly with increasing x. These changes in magnetic moments and structures are reflected in anomalous expansions of the lattice parameters, indicating strong magneto-elastic coupling. Lastly, the magnetocaloric properties of the solid solutions were explored. For x = 0.2 the isothermal entropy change (δSm) is smaller by 30% than it is for Fe2AlB2, while the relative cooling power is larger by 6%, due to broadening of the temperature range of the transition.
Citation
Physical Review Materials
Volume
4
Issue
8

Keywords

Neutron diffraction
Created August 5, 2020, Updated September 8, 2020