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Issue 46, 2016
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Observation of room temperature magnetodielectric effect in Mn-doped lanthanum gallate and study of its magnetic properties

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Abstract

Polycrystalline samples of Mn-doped LaGa1−xMnxO3 (LGMO) with 0 ≤ x ≤ 0.2 have been prepared via solid-state reaction method. The structural phase purity of all these samples was confirmed by powder X-ray diffraction experiments carried out at the BL-12 beamline of the Indus-2 synchrotron radiation source. Room-temperature (RT) dielectric measurements were performed in the absence and presence of a magnetic field. A noticeable magnetodielectric (MD) effect, i.e., a change in the value of the dielectric constant owing to the application of a low magnetic field, was observed in the LGMO sample with x = 0.2 (LG8M2O). In order to separate the intrinsic and resistive contributions present in the observed RT MD effect, magnetoresistance impedance spectroscopy (MRIS) was performed at RT. The present MRIS analysis suggests that at frequencies corresponding to the grain contribution (≥105 Hz for the present samples), the observed MD phenomenon appears to be an intrinsic property of the presently studied samples, whereas at lower probing frequencies (<105 Hz) the observed change appears to be dominated by MR (considering frequency-dependent resistance), which was possibly due to the coexistence of Mn3+ and Mn4+. The coexistence of Mn3+ and Mn4+ was revealed by XANES (Mn K-edge) spectroscopy. Moreover, RT and low-temperature magnetization–magnetic field (MH) measurements, along with MT measurements in FC and ZFC modes, were performed to investigate the state of magnetic ordering. The appearance of a narrow MH loop indicates the presence of some magnetic ordering at RT. Furthermore, a ferromagnetic (FM) transition observed around 36 K and a normal MH loop with saturated magnetization recorded at 5 K confirm FM ordering at low temperatures, whereas a bifurcation in FC-ZFC curves indicates competing FM and antiferromagnetic (AFM) interactions at low temperatures.

Graphical abstract: Observation of room temperature magnetodielectric effect in Mn-doped lanthanum gallate and study of its magnetic properties

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Publication details

The article was received on 23 Aug 2016, accepted on 24 Oct 2016 and first published on 26 Oct 2016


Article type: Paper
DOI: 10.1039/C6TC03641D
Citation: J. Mater. Chem. C, 2016,4, 10876-10886
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    Observation of room temperature magnetodielectric effect in Mn-doped lanthanum gallate and study of its magnetic properties

    H. M. Rai, S. K. Saxena, V. Mishra, A. Sagdeo, P. Rajput, R. Kumar and P. R. Sagdeo, J. Mater. Chem. C, 2016, 4, 10876
    DOI: 10.1039/C6TC03641D

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