Magnetically tunable alternating current electrical properties of x La0.7Sr0.3MnO3–(1 − x) ErMnO3 (x = 0.1, 0.3, and 0.5) multiferroic nanocomposite

Abstract

Detailed magnetically tunable ac electrical properties of x La0.7Sr0.3MnO3 (LSMO)–(1 − x) ErMnO3 (EMO) (x = 0.1, 0.3, and 0.5) multiferroic nanocomposites have been studied at 300 K in presence of varying magnetic field (Happl), applied both in parallel and perpendicular configuration with respect to the measuring electric field. AC electrical properties have exhibited significant variation with Happl for all composites, whereas for parallel configuration of Happl such effect is very feeble for x = 0.3 composite. We have attributed this anisotropic behavior to the demagnetization effect in the sample. In contrast, for x = 0.1 and 0.5 composites, no such anisotropy effect is experimentally evidenced. Impedance and real part of impedance have been found to decrease with Happl at low frequency (f) region. We attribute this observation to the depinning of the magnetic domain walls from the grain boundaries pinning centers and thereby enhancing the spin dependent transport in the composite. For x = 0.3 composite, Nyquist plots have been fitted considering dominant contributions of LSMO and EMO grain boundaries and the interface region between them. However, for x = 0.1 composite, it corresponds to EMO grain boundaries and grain boundary interface region. The relaxation frequency (fR) is observed to shift at higher/lower f region in perpendicular/parallel configuration of Happl for x = 0.3 composite. This opposite variation of fRs with Happl for perpendicular and parallel configurations has been attributed to two competing factors of Happl induced enhancement of inductive part and Happl enhanced spin dependent transport causing fast relaxation processes in the sample. For x = 0.1 composite, in both configurations of Happl, fRs is shifting towards high f region, which has been discussed in terms of dominant role of spin dependent transport.