DC transport properties and microwave absorption in bulk ceramic sample and film of La_{0.5}Sr_{0.5}CoO_{3-\delta}: magnetic inhomogeneity effects

TL;DR

This study investigates the DC and microwave transport properties of La_{0.5}Sr_{0.5}CoO_{3-elta} in bulk and film forms, revealing significant microwave conductivity increases linked to magnetic inhomogeneity.

Contribution

It provides new insights into the magnetic inhomogeneity effects on microwave absorption and transport properties in doped cobaltates.

Findings

Microwave conductivity increases by an order of magnitude at ferromagnetic transition.

Microwave effects are attributed to inherent magnetic inhomogeneity.

Low magnetoresistance is linked to magnetic inhomogeneity in cobaltates.

Abstract

The DC transport properties and microwave absorption (at 41 GHz) are measured in a bulk ceramic sample and a film (220 nm thick) of La$_{0.5}$Sr$_{0.5}$CoO$_{3-\delta}$. The samples are polycrystalline. The microwave conductivity, which is related mainly to the intragrain conductivity, increases by the order of the magnitude at the transition to the ferromagnetic state. The increase is far greater than that of found in the known DC measurements in doped cobaltates of the best crystal perfection. The found microwave effect is attributed to inherent magnetically inhomogeneous state of the doped cobaltates. Relaying on the results obtained it can be suggested that rather low magnetoresistance in the doped cobaltates as compared with that of the manganites is attributable to their more inhomogenenous magnetic state.