Antisymmetric exchange in La-substituted BiFe0.5Sc0.5O3 system: symmetry adapted distortion modes approach
authors Khalyavin, DD; Salak, AN; Manuel, P; Olekhnovich, NM; Pushkarev, AV; Radysh, YV; Fedorchenko, AV; Fertman, EL; Desnenko, VA; Ferreira, MGS
nationality International
journal ZEITSCHRIFT FUR KRISTALLOGRAPHIE-CRYSTALLINE MATERIALS
author keywords antisymmetric exchange; multiferroics; perovskites
keywords WEAK FERROMAGNETISM; THERMODYNAMIC THEORY; PEROVSKITES
abstract Neutron powder diffraction measurements on the 35 % La-substituted Bi1-xLaxFe0.5Sc0.5O3-composition revealed that the samples obtained under high-pressure (6 GPa) and high-temperature (1500 K) conditions crystalize into a distorted perovskite structure with the orthorhombic Pnma symmetry and the unit cell para-meters: a(0) = 5.6745(2) angstrom, b(0) = 7.9834(3) angstrom and c(0) = 5.6310(2) angstrom. A long-range magnetic ordering takes place below 220 K and implies a G-type magnetic structure with the moments 4.10(4)mu(B) per Fe aligned predominately along the orthorhombic c-axis. The space group representation theory using the orthorhombic symmetry yields four bi-linear coupling schemes for the magnetic order parameters imposed by antisymmetric exchange interactions. The couplings are analysed based on symmetry adapted distortion modes defined in respect of the undistorted cubic perovskite structure. The approach allows a quantitative estimation of the coupling strength. It is shown that the experimentally found spin configuration combines the magnetic order parameters coupled by the atomic displacement modes with the largest amplitudes. The results indicate that the antisymmetric exchange is the dominant anisotropic term which fully controls the direction of the Fe3+ spins in the distorted perovskite lattice.
publisher WALTER DE GRUYTER GMBH
issn 2194-4946
year published 2015
volume 230
issue 12
beginning page 767
ending page 774
digital object identifier (doi) 10.1515/zkri-2015-1873
web of science category Crystallography
subject category Crystallography
unique article identifier WOS:000365870300009
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journal impact factor (jcr 2016): 3.179
5 year journal impact factor (jcr 2016): 1.843
category normalized journal impact factor percentile (jcr 2016): 75.000
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