Giant radio-frequency magnetoabsorption effect in the cobaltite ceramic La_{0.5}Sr_{0.5}CoO_3

TL;DR

This study reports a giant negative magnetoabsorption effect at radio frequencies in La_{0.5}Sr_{0.5}CoO_3 ceramics near its Curie temperature, significantly larger than its DC magnetoresistance, with potential applications in RF device control.

Contribution

It reveals a large RF magnetoabsorption effect in cobaltite ceramics, highlighting its dependence on magnetic field and temperature, distinct from DC magnetoresistance.

Findings

Magnetoabsorption reaches about 38% near T_c in low magnetic fields.

DC magnetoresistance is much smaller, about 0.26% near T_c.

The effect is due to magnetic field influence on conductivity and permeability.

Abstract

The DC transport properties of and the radio-frequency (RF) wave absorption (at 1.33 MHz) in a ceramic sample of La_{0.5}Sr_{0.5}CoO_{3-\delta} are measured. The Curie temperature, T_{c}, of the sample is about 250 K. A giant negative magnetoabsorption effect is found. In the vicinity of T_{c}, the absolute value of the magnetoabsorption is about 38 % in the rather low magnetic field 2.1 kOe. This differs drastically from the measured DC magnetoresistance (MR) \delta (H) =[R(0)-R(H)]/R(0) which is a mere 0.26 % near T_{c}in the same field and increases to about 2.15 % in H=20 kOe. The phenomenon can be understood taking into account that the magnetoabsorption is determined by influence of magnetic field on the conductivity and the magnetic permeability, while the MR is determined solely by the former. The magnetoabsorption effect can be used to develop RF devices controlled by magnetic field and temperature.