Magneto-dielectric coupling and non-ergodic electrical behaviour in hexagonal Sr0.6Ba0.4MnO3 via local strain driven magnetic ordering

TL;DR

This study investigates the complex magnetic and electrical behaviors of hexagonal Sr0.6Ba0.4MnO3, revealing local strain-driven magnetic ordering, non-ergodic electrical glassiness, and the interplay of superexchange interactions affecting its properties.

Contribution

It uncovers the role of local strain and superexchange interactions in driving magnetic ordering and electrical glassiness in hexagonal Sr0.6Ba0.4MnO3, providing new insights into its non-ergodic behavior.

Findings

Short-range magnetic correlations drop below 325K.

Long-range correlations emerge below 225K.

Electrical relaxation time diverges power-law-like upon cooling.

Abstract

The crystal structure of hexagonal-Sr0.6Ba0.4MnO3 allows various competing superexchange interactions, leading to intriguing magnetic properties. Local structural changes modify overlapping between Mn and oxygen ions with temperature. Calculations based on our model spin-Hamiltonian reveal that the dominant linear antiferromagnetic superexchange interaction between the oxygen-linked Mn4+ ions results in short range correlations (SRC), manifesting a smooth drop in magnetization below 325K. Dominance of superexchange interaction changes its allegiance towards the non-linear oxygen-linked Mn-O-Mn interactions, onsetting long-range correlations (LRC) below 225K. Below the SRC-LRC crossover temperature, electrical response arising from the interacting dipoles exhibits power-law divergent behaviour of relaxation time, upon cooling. Non-ergodic character of the dipole-cluster glass state is examined via the indispensable aging and rejuvenation effects, similar to the spin glasses. Competitive-frustration among spin-exchange and local-strain is reckoned as responsible for the electrical glass origin.