Room temperature magnetodielectric studies on Mn-doped LaGaO₃

Abstract

Abstract:The polycrystalline samples of LaGa 1-x Mn x O 3 (0<x<0.3) has been prepared by solid state reaction route. The phase purity of these samples has been confirmed by powder x-ray diffraction experiments carried out on BL-12 at Indus-2 synchrotron radiation source. The sample with x=0.2 shows significant change in the value of capacitance with the application of magnetic field. The observed results were understood by systematically analyzing magnetocapacitance (MC), magneto resistance (MR) and dielectric loss as a function of frequency. Our results and analysis suggests that the observed magneto dielectric (MD) coupling may be due to the MR effect of Maxwell-Wagner type and/or field induced dipolar relaxation. Further it is observed that the oxygen stoichiometry plays a very crucial role in observed MD coupling.

Observation of large dielectric permittivity and dielectric relaxation phenomenon in Mn-doped lanthanum gallate

“…Moreover, the appearance of a large 3 0 in some compounds having unlled and unscreened subshells such as rare-earth metal tungstates, has been attributed to the eld-induced polarization. 16,17 Recently we have demonstrated the magneto-dielectric effect at room temperature in Mn-doped LaGaO 3 (LGO) 18 and in the present article we report the appearance of a large 3 0 along with dielectric relaxation in Mndoped lanthanum gallate (LGO).…”

Room-Temperature Magneto-dielectric Effect in LaGa0.7Fe0.3O3+γ; Origin and Impact of Excess Oxygen

“…Since no negative dc MR is observed, the present MD effect appears to be dc MR-free. However, (i) as the observed shifting of tan δ-peak position toward higher frequency due to applied field ( H = 0.2 to 1.2 T) is indicating toward the presence of resistive component and (ii) as FDMR measurements are supposed to be more sensitive in such a case, therefore, to get a better view about the contribution of MR in observed effect, FDMR (20 Hz to 10 MHz) was also analyzed by means of MRIS (MR via impedance spectroscopy) measurements. These RT measurements were performed in the absence ( H = 0.0 T) and presence ( H = 0.2 to 1.2 T) of magnetic field to record the real ( Z ′) and imaginary ( Z ″) part of impedance.…”

“…Besides the values of temperature and magnetic field, intrinsicality of the observed effect is also important from basic physics as well as application point of view, as the MD effect may appear also due to extrinsic magnetoresistive artifacts. , By means of some excellent theoretical modeling, G. Catalan provided a way to judge the intrinsicality of observed MD effect, which has been widely accepted and followed by others. ,− Nevertheless, Lawes et al pointed out that MD response may appear significantly near structural transition temperatures of material. Reports , on LGO perovskite compound suggest that the temperature for its structural phase transition (∼418 K , ) is decreased due to doping and that it exhibits different interesting phenomena due to transition-metal (TM) doping. ,− Additionally, the ionic radius of Ga ion is different than that of the TM ions; therefore, TM doping at Ga site may induce orthorhombic distortion/strain in LGO. Hence, it is reasonable to expect that the doping with magnetic TM ions in LGO-type dielectric compound may lead to MD coupling near/at RT either due to some structural phase transition or through magnetically switchable structural distortions.…”

Dielectric relaxation and magnetodielectric response of mesoporous terbium manganate nanopaticles

“…where C bal is a constant, L is sample height, m is sample mass.R and R 0 are the digital readings for sample filled tube [46][47][48] reported the presence of magnetoelectric coupling in the paramamagnetic state of metal-organic framework and rare earth molybdates respectively. In the present sample, further study is done to observe the nature of magnetoelectric coupling at room temperature.…”

“…The change in the value of ∕ and tan is higher in low frequency region than that of high frequency range. It suggests that the grain boundaries are more sensitive to the magnetic field than the intrinsic grains [48]. Figure 9b shows the magnetic field dependence of dielectric loss (tan ) at different frequencies.…”