Discovery of new magnetic orders on pyrochlore spinels

TL;DR

This paper uncovers new magnetic orders in pyrochlore spinels caused by anisotropic spin exchanges, revealing complex phases and their potential effects on electronic properties, advancing understanding of frustrated magnetic systems.

Contribution

It introduces novel magnetic phases induced by anisotropic interactions in pyrochlore spinels, including states with finite wavevectors and their implications for magnetic and electronic phenomena.

Findings

Identification of classical spin states such as local XY, all-in all-out, Palmer-Chalker, and coplanar spiral.

Discovery of new magnetic phases with finite ordering wavevectors, like 'octagonal (prism)' and '(distorted) cubic' states.

Demonstration of scalar spin chirality leading to net currents in certain magnetic phases.

Abstract

Frustration in spin system can give rise to unique ordered states and as a consequence several physical phenomena are expected such as multiferroics, high temperature superconductors and anomalous hall effect. Here we report the "new magnetic orders" induced by anisotropic spin exchanges on pyrochlore spinels as the interplay of spin orbit coupling and geometrical frustration. Due to complicated superexchange paths of B-site spinels, we claim that anisotropic interaction between next-nearest neighbors play an important role. Based on the systematic studies of generic spin model, we argue that several classical spin states can be explored in spinel systems; local XY state, all-in all-out state, Palmer-Chalker state and coplanar spiral state. In addition, we reveal new types of magnetic phases with finite ordering wavevectors, labeled as 'octagonal (prism)' state and '(distorted) cubic' states. When the 'octagonal prism' state is stabilized, non-zero scalar spin chirality induces alternating net current in addition to finite orbital current and orbital magnetization even in Mott insulators. Finally, we also discuss the relevance of 'distorted cubic' state to the magnetic order of spinel compound GeCo2O4.