Magneto-Dielectric phenomena in charge and spin frustrated system of layered iron oxide

TL;DR

This study investigates magneto-dielectric phenomena in RFe2O4, revealing charge and spin frustration effects, charge order stabilization, and cross-correlation responses to magnetic and electric fields through theoretical modeling and simulations.

Contribution

It introduces a detailed electronic model for RFe2O4 and demonstrates how spin frustration and charge-spin coupling lead to novel magneto-dielectric effects.

Findings

Charge-ordered structure stabilized at finite temperatures.

Spin ordering reinforces the polar charge order.

Cross-correlation effects in magnetic and electric responses.

Abstract

Dielectric and magnetic phenomena in spin and charge frustrated system RFe2O4 (R is a rare-earth metal ion) are studied. An electronic model for charge, spin and orbital degrees in a pair of triangular-lattice planes is derived. We analyze this model by utilizing the mean-field approximation and the Monte-Carlo simulation in a finite size cluster. A three fold-type charge ordered structure with charge imbalance between the planes is stabilized in finite temperatures. This polar charge order is reinforced by spin ordering of Fe ions. This novel magneto-dielectric phenomenon is caused by spin frustration and charge-spin coupling in the exchange interaction. We show cross-correlation effect in magnetic- and electric-field responses. Oxygen deficiency effect as an impurity effect in a frustrated charge-spin coupled system is also examined.