Giant magneto-impedance in Ag-doped La0.7Sr0.3MnO3

TL;DR

This study investigates the frequency-dependent magneto-impedance properties of Ag-doped La0.7Sr0.3MnO3, revealing significant changes at high frequencies and proposing a phenomenological model to describe the behavior.

Contribution

It introduces a comprehensive analysis of magneto-impedance in Ag-doped La0.7Sr0.3MnO3 and proposes a new phenomenological formula based on Pade approximant.

Findings

Maximum relative change in resistance ~70% at 15MHz and 4KOe

Normalized magneto-impedance is frequency independent when scaled

Magneto-impedance is negative across all frequencies

Abstract

The resistive and reactive parts of the magneto-impedance of sintered ferromagnetic samples of La0.7Sr0.3-xAgxMnO3 (x = 0.05, 0.25) have been measured at room temperature (<Tc) over frequency interval 1KHz to 15MHz and in presence of magnetic field up to 4KOe. The field dependence of relative change in resistance is small in KHz region but increases strongly for higher frequency of excitation. The maximum value of relative change in resistance at H =4KOe was found to be around 70% at 15MHz frequency.On the contrary the corresponding change in reactance has less frequency sensitivity and the maximum occurs at 1MHz frequency. The magneto-impedance is negative for all frequencies. The 'normalized magneto-impedance' as defined by [Z(H)-Z(0)]/[Z(0)-Z(4K)] when plotted against scaled field H/H1/2 is found to be frequency independent ; H1/2 is the field where 'normalized magneto-impedance' is reduced to half its maximum. A phenomenological formula for magneto-impedance Z (H) in ferromagnetic material is proposed based on Pade approximant. The formula for Z (H) predicts the scaled behavior of 'normalized magneto-impedance'.