Relaxations as key to the magnetocapacitive effects in the perovskite manganites

TL;DR

This study investigates dielectric relaxation effects in perovskite manganites, revealing that magnetocapacitive effects are mainly driven by magnetic-state-induced changes in relaxation parameters, linked to manganese ion off-center motion.

Contribution

It provides a detailed analysis showing how magnetic states influence dielectric relaxations and magnetocapacitive effects in multiferroic and antiferromagnetic manganites.

Findings

Magnetocapacitive effects are governed by magnetic-state induced relaxation changes.

Different magnetic states lead to distinct relaxation behaviors.

Relaxations are attributed to off-center manganese ion motion.

Abstract

We present a detailed dielectric study of the relaxation effects that occur in several perovskite rare-earth manganites, including the multiferroics TbMnO3 and DyMnO3. We demonstrate that the strong magnetocapacitive effects, observed for electrical fields E||c, are nearly completely governed by magnetic-state induced changes of the relaxation parameters. The multiferroic materials, which undergo a transition into a spiral magnetic state, show qualitatively different relaxation behavior than those compounds transferring into an A-type antiferromagnetic state. We ascribe the relaxations in both cases to the off-center motion of the manganese ions, which in the multiferroic systems also leads to the ferroelectric ordering.