Magnetic ordering and conduction mechanism of different electroactive regions in Lu2NiMnO6

The magnetodielectric response of a double perovskite oxide Lu2NiMnO6 (LNMO) synthesised by the sol–gel process has been investigated. The Rietveld refinement of the X-ray diffraction data indicates that the room-temperature crystal structure of LNMO is monoclinic with the space group P21/n, which c...

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Veröffentlicht in:Journal of applied physics 2016-10, Vol.120 (13)
Hauptverfasser: Chanda, Sadhan, Saha, Sujoy, Dutta, Alo, Krishna Murthy, J., Venimadhav, A., Shannigrahi, Santiranjan, Sinha, T. P.
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Sprache:eng
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Zusammenfassung:The magnetodielectric response of a double perovskite oxide Lu2NiMnO6 (LNMO) synthesised by the sol–gel process has been investigated. The Rietveld refinement of the X-ray diffraction data indicates that the room-temperature crystal structure of LNMO is monoclinic with the space group P21/n, which contains an ordered array of alternate MnO6 and NiO6 octahedra. X-ray photoelectron spectroscopy studies confirm the mix valence state of Mn (4+ and 3+) and Ni (2+ and 3+). The optical band gap (Eg = 1.56 eV) obtained from the UV-Visible absorption spectrum suggests that LNMO is a semiconductor. The field cooled and zero-field cooled measurements show the ferromagnetic behaviour of the sample with the transition temperature (Tc) = 45 K and a saturation magnetization of 5.2 μB/f.u. is observed at 2.5 K. The temperature and frequency dependent dielectric measurements reveal colossal values of the dielectric constant, which are interpreted by the Maxwell-Wagner interfacial polarization. The temperature dependence of the bulk dc conductivity indicates a variable-range-hopping mechanism. The saturation polarization value is estimated to be 232 μC/m2 from the pyroelectric current measurement. A negative magnetodielectric effect of 1% is observed at the paramagnetic to ferromagnetic transition temperature. The electronic structure calculations based on density functional theory have been performed to analyse the magnetic properties of LNMO.
ISSN:0021-8979
1089-7550
DOI:10.1063/1.4963824