Large Magneto-Dielectric Effects in Orthorhombic HoMnO3 and YMnO3

TL;DR

This study demonstrates a significant magneto-dielectric effect in orthorhombic HoMnO3 and YMnO3, with dielectric constants increasing up to 60% at magnetic transition temperatures, highlighting strong coupling between magnetic and dielectric properties.

Contribution

It reveals the large magneto-dielectric effects in orthorhombic HoMnO3 and YMnO3 and distinguishes the contributions of Mn and Ho magnetic orders to this coupling.

Findings

Dielectric constant increases up to 60% at magnetic transition.

Magnetic field can tune dielectric response, reducing it by 8% at 7 Tesla.

Distinct anomalies and hysteresis observed at magnetic ordering and lock-in transitions.

Abstract

We have found a remarkable increase (up to 60 %) of the dielectric constant with the onset of magnetic order at 42 K in the metastable orthorhombic structures of YMnO3 and HoMnO3 that proves the existence of a strong magneto-dielectric coupling in the compounds. Magnetic, dielectric, and thermodynamic properties show distinct anomalies at the onset of the incommensurate magnetic order and thermal hysteresis effects are observed around the lock-in transition temperature at which the incommensurate magnetic order locks into a temperature independent wave vector. The orders of Mn3+ spins and Ho3+ moments both contribute to the magneto-dielectric coupling. A large magneto-dielectric effect was observed in HoMnO3 at low temperature where the dielectric constant can be tuned by an external magnetic field resulting in a decrease of up to 8 % at 7 Tesla. By comparing data for YMnO3 and HoMnO3 the contributions to the coupling between the dielectric response and Mn and Ho magnetic orders are separated.