Magnetism and topology in Tb-based icosahedral quasicrystal

TL;DR

This paper provides a microscopic analysis of the crystal electric field in Tb-based quasicrystals, revealing how magnetic anisotropy leads to unique magnetic textures and topological states, and how these can be controlled via composition.

Contribution

It introduces a detailed microscopic model for magnetic and topological properties in Tb-based quasicrystals, highlighting the role of crystal electric field effects.

Findings

Magnetic anisotropy from CEF stabilizes hedgehog magnetic order.

Large topological charge in whirling-moment states.

Magnetic textures can be controlled by composition changes.

Abstract

Quasicrystal (QC) possesses a unique lattice structure with rotational symmetry forbidden in conventional crystals. The electric property is far from complete understanding and it has been a long-standing issue whether the magnetic long-range order is realized in the QC. The main difficulty was lack of microscopic theory to analyze the effect of the crystalline electric field (CEF) at the rare-earth atom in QCs. Here we show the full microscopic analysis of the CEF in Tb-based QCs. We find that magnetic anisotropy arising from the CEF plays a key role in realizing unique magnetic textures on the icosahedron whose vertices Tb atoms are located at. Our analysis suggests that the long-range order of the hedgehog characterized by the topological charge of one is stabilized in the Tb-based QC. We also find that the whirling-moment state is characterized by unusually large topological charge of three. The magnetic textures as well as the topological states are shown to be switched by controlling compositions of the non-rare-earth elements in the ternary compounds. Our model is useful to understand the magnetism as well as the topological property in the rare-earth-based QCs and approximant crystals.