Spin and Orbital Effects on Asymmetric Exchange Interaction in Polar Magnets: M(IO3)2 (M = Cu, Mn)

TL;DR

This study investigates how spin and orbital effects influence Dzyaloshinskii-Moriya interactions in polar magnets Cu(IO3)2 and Mn(IO3)2, revealing their structural, magnetic, and topological properties and how these factors can be tuned for novel spin phases.

Contribution

It provides new insights into the role of spin-orbit coupling and orbital effects in asymmetric exchange interactions within polar transition-metal io-dates.

Findings

Cu(IO3)2 exhibits incommensurate magnetic order influenced by orbital effects.

Mn(IO3)2 shows a commensurate stripe AFM ground state with quenched orbital angular momentum.

Both materials have polar, chiral structures with potential for topological spin phases.

Abstract

We study how spin and orbital effects influence the capability of promoting Dzyaloshinskii-Moriya (DM) interaction by studying the two magnetic polar materials, Cu(IO3)2 (S = 1/2 with orbital contribution) and Mn(IO3)2 (S = 5/2 with quenched orbital magnetism) and connecting their electronic and magnetic properties with their structures. The chemically controlled low-temperature synthesis of these complexes resulted in pure polycrystalline samples, providing a viable pathway to prepare bulk forms of transition-metal io-dates. Rietveld refinements of the powder synchrotron X-ray diffraction data reveal that these materials exhibit different crystal structures but crystallize in the same polar and chiral P21 space group, giving rise to an electric polarization along the b-axis direction. The presence and absence of an evident phase transition to a possible topologically distinct state observed in Cu(IO3)2 and Mn(IO3)2, respectively, implies the important role of spin-orbit coupling. Neutron diffraction experiments reveal helpful insights into the magnetic ground state of these materials. While the long-wavelength incommensurability of Cu(IO3)2 is in harmony with orbital effects and anisotropic magnetic exchange, the commensurate stripe AFM ground state of Mn(IO3)2 is attributed to quenched orbital angular momentum and isotropic magnetic coupling. The work demonstrates connections between combined spin and orbital effects, magnetic coupling dimensionality and DM exchange, providing a worthwhile approach for tuning asymmetric interaction which promotes evolution of topologically distinct spin phases.