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arXiv · 1910.14446

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

Ritu Rawat·R. J. Choudhary·A. M. Awasthi·Rajamani Raghunathan·Archna Sagdeo·A. K. Sinha·S. Chaudhary·S. Patnaik·D. M. Phase
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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.

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Ritu Rawat, R. J. Choudhary, A. M. Awasthi, Rajamani Raghunathan, Archna Sagdeo, A. K. Sinha, S. Chaudhary, S. Patnaik, D. M. Phase. 2019-10-30. Magneto-dielectric coupling and non-ergodic electrical behaviour in hexagonal Sr0.6Ba0.4MnO3 via local strain driven magnetic ordering. https://doi.org/10.1016/j.jmmm.2019.165972

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