Modified Heisenberg model for the zig-zag structure in multiferroic RMn{sub 2}O{sub 5}

Journal Article · Fri Aug 28 04:00:00 EDT 2015 · Journal of Applied Physics

DOI:https://doi.org/10.1063/1.4929646· OSTI ID:22494792

Trimper, Steffen ^[1]

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1. Institute of Physics, Martin-Luther-University Halle-Wittenberg, D-06099 Halle (Germany)

The class of RMn{sub 2}O{sub 5} (R = Ho, Tb, Y, Eu) compounds offers multiferroic properties where the refined magnetic zig-zag order breaks the inversion symmetry. Varying the temperature, the system undergoes a magnetic and a subsequent ferroelectric phase transition where the ferroelectricity is magnetically induced. We propose a modified anisotropic Heisenberg model that can be used as a tractable analytical model studying the properties of those antiferromagnetic zig-zag spin chains. Based on a finite temperature Green's function method, it is shown that the polarization is induced solely by different exchange couplings of the two different Mn{sup 4+} and Mn{sup 3+} magnetic ions. We calculate the excitation energy of the spin system for finite temperatures, which for its part determines the temperature dependent magnetization and polarization. The ferroelectric phase transition is manifested as a kink in the excitation energy. The variation of the polarization by an external magnetic field depends strongly on the direction of that field. Whereas, the polarization in b-direction increases with an external magnetic field as well in b-direction it can be switched for strong fields in a-direction. The results based on that modified Heisenberg model are in qualitative agreement with experimental data.

• OSTI ID: 22494792
• Journal Information: Journal of Applied Physics, Journal Name: Journal of Applied Physics Journal Issue: 8 Vol. 118; ISSN JAPIAU; ISSN 0021-8979
• Country of Publication: United States
• Language: English

Related Subjects

71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
ANISOTROPY
ANTIFERROMAGNETISM
EUROPIUM COMPOUNDS
EXCITATION
EXPERIMENTAL DATA
FERROELECTRIC MATERIALS
HEISENBERG MODEL
HOLMIUM COMPOUNDS
MAGNETIC FIELDS
MAGNETIZATION
MANGANESE IONS
PHASE TRANSFORMATIONS
POLARIZATION
SPIN
SYMMETRY
TEMPERATURE DEPENDENCE
TERBIUM COMPOUNDS
YTTRIUM COMPOUNDS