Evidence for large electric polarization from collinear magnetism in TmMnO3

TL;DR

This study demonstrates that collinear magnetic order in orthorhombic TmMnO3 induces significant ferroelectric polarization, exceeding previous heavy rare-earth manganites, with strong spin-lattice coupling effects observed.

Contribution

It provides experimental evidence that collinear magnetism can induce large ferroelectric polarization in TmMnO3, expanding understanding of magneto-electric coupling in orthorhombic perovskites.

Findings

Ferroelectric polarization in TmMnO3 exceeds that in other orthorhombic manganites.

Large spin-lattice coupling effects are observed through lattice constant measurements.

Polarization potentially surpasses the 1 microC/cm2 threshold predicted by theory.

Abstract

There has been tremendous research activity in the field of magneto-electric (ME) multiferroics after Kimura et al. [1] showed that antiferromagnetic and ferroelectric order coexist in orthorhom- bically distorted perovskite TbMnO3 and are strongly coupled. It is now generally accepted that ferroelectricity in TbMnO3 is induced by magnetic long range order that breaks the symmetry of the crystal and creates a polar axis [2]. One remaining key question is whether magnetic order can induce ferroelectric polarization that is as large as that of technologically useful materials. We show that ferroelectricity in orthorhombic (o) TmMnO3 is induced by collinear magnetic order, and that the lower limit for its electric polarization is larger than in previously investigated orthorhombic heavy rare-earth manganites. The temperature dependence of the lattice constants provides fur- ther evidence of large spin-lattice coupling effects. Our experiments suggest that the ferroelectric polarization in the orthorhombic perovskites with commensurate magnetic ground states could pass the 1 microC/cm2 threshold, as suggested by theory [3, 4].