Impact of Fe doping on radiofrequency magnetotransport in La 0.7Sr 0.3Mn 1-xFe xO 3

Abstract

We report four probe ac electrical impedance (Z) in La 0.7Sr 0.3Mn 1-xFe xO 3 (x ≤ 0.15) as a function of temperature (T) and magnetic field (H) in response to radio frequency (f 0.1-5 MHz) ac current flowing directly through the sample. It is found that Z(T,H 0) shows an abrupt increase around Curie temperature with increasing f and this excess resistance is suppressed under an external magnetic field. A large magnetoimpedance of δZ/Z -21 at f 1 MHz for x = 0.05 and -8.5 at f 5 MHz for x = 0.15 are observed for H 500 Oe. We suggest that the magnetoimpedance results from suppression of the high frequency transverse permeability by an external magnetic field. Optimization of composition and frequency of ac current will enable us to obtain much larger low-field magnetoimpedance value suitable for practical applications at room temperature. © 2012 American Institute of Physics.