Magnetic structure of the kagome metal YbFe6Ge6 in view of Bragg diffraction

TL;DR

This study investigates the complex magnetic structure of the kagome metal YbFe6Ge6 using Bragg diffraction, revealing independent Yb magnetism, a temperature-induced magnetic transition, and rich Fe magnetic phenomena with potential for future experimental exploration.

Contribution

It provides detailed symmetry-based analysis of YbFe6Ge6's magnetic structure, highlighting independent Yb magnetism and complex Fe magnetic properties, advancing understanding of kagome metals.

Findings

Fe moments undergo collinear antiferromagnetic order below 500 K

Yb magnetism appears independent and is confirmed via resonant x-ray diffraction

Rich magnetic phenomena including space-spin correlations, anapoles, and Dirac quadrupoles

Abstract

A material in possession of localized 4f-electron magnetism and delocalized 3d-electron or band magnetism can often present A material in possession of localized 4f-electron magnetism and delocalized 3d-electron or band magnetism can often present enigmatic physical phenomena, and there has been a longstanding interest in the kagome metal YbFe6Ge6. More recently, because of an investigation of a so-called anomalous Hall effect, or topological Hall effect, and magnetic neutron Bragg diffraction [W. Yao et al., Phys. Rev. Lett. 134, 186501 (2025)]. Iron moments in the two-dimensional layers of a hexagonal nuclear structure undergo collinear antiferromagnetic order below a temperature 500 K. The moments depart from the c axis in a spontaneous transition at 63 K to an orthorhombic structure. The magnetism of Yb ions appears to behave independently, which can be confirmed using resonant x-ray diffraction enhanced by a Fe atomic resonance. The inferred magnetic space group is a P(parity)T(time)-symmetric (anti-inversion collinear antiferromagnet. A linear magnetoelectric effect is allowed, as in historically important chromium sesquioxide, and Kerr rotation and the piezomagnetic effect are forbidden. Symmetry informed Bragg diffraction patterns for future x-ray and neutron experiments are shown to be rich in Fe magnetic properties of orthorhombic YbFe6Ge6, including space-spin correlations, anapoles and Dirac quadrupoles familiar in high-Tc ceramic superconductors.