The intrinsic exchange bias effect in the LaMnO3 and LaFeO3 compounds

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Authors

Colleges, School and Institutes

External organisations

  • University of Oviedo

Abstract

This work investigates the magnetic and the intrinsic exchange bias (EB) properties of the sol-gel synthesised LaMnO3 and LaFeO3 perovskite compounds. The x-ray diffraction (XRD) has proved the high homogeneity of both compounds, which are crystallised in the orthorhombic Pnma structure (as proved by Rietveld refinement). The field cooling-zero field cooling magnetisation dependent temperature (M(T)) indicates the antiferromagnetic (AFM) nature of these compounds. Nevertheless, an anomalous ferromagnetic (FM) behaviour is observed, which is more likely, arises from the spin canting effect in the Mn3+ and Fe3+ ions. The thermal variation of the magnetisation reciprocal (M−1) has confirmed the presence of this FM component below 110K in LaMnO3 and the Curie-Weiss behaviour above 160K. Also, the magnetic hysteresis loops below 110K are corresponding to the FM-like behaviour. The spin of the FM component couples with the AFM phase spins, leading to the EB effect in both compounds that show maximum values of −1124Oe and 2343 Oe for the LaMnO3 and LaFeO3 compounds, respectively. It is observed that the EB effect is suppressed with the partial substitution of La3+ by Ba2+ due to the dominance of the FM phase and the absence of the FM/AFM coupling. Also, the influence of the FM-AFM phases co-existence on the magnetocaloric(MCE) properties of the LaMnO3 compound were studied. Where the LaMnO3 compound shows a magnetic entropy change (ΔS) of 0.42 J/kg.K with an adiabatic temperature change (ΔTad) of 0.1k that is improved in the La0·8Ba0·2MnO3 compound to 1.3 J/kg.K and 0.4K, respectively.

Details

Original languageEnglish
Article number156713
Pages (from-to)156713-156720
Number of pages8
JournalJournal of Alloys and Compounds
Volume850
Early online date14 Aug 2020
Publication statusPublished - 5 Jan 2021

Keywords

  • Exchange bias, Magnetic properties, Magnetocaloric effect, Manganites, Rare earth alloys and compounds, Spin canting