Tunable topological transitions in the frustrated magnet HoAgGe

TL;DR

This paper investigates how magnetic frustration and spin-ice states in HoAgGe influence electronic topology, revealing sharp Hall conductivity transitions driven by external magnetic fields, highlighting complex interplay between magnetism and electronic structure.

Contribution

It demonstrates field-induced topological transitions in HoAgGe driven by magnetic frustration, combining experimental and theoretical methods to reveal complex spin-electronic interactions.

Findings

Sharp Hall conductivity transitions without magnetization change

Spin-ice states influence Fermi surface topology

Limitations of simple spin-ice models highlighted

Abstract

The kagome lattice, known for its strong frustration in two dimensions, hosts a variety of exotic magnetic and electronic states. A variation of this geometry, where the triangular motifs are twisted to further reduce symmetry, has recently revealed even more complex physics. HoAgGe exemplifies such a structure, with magnetic and electronic properties believed to be driven by strong in-plane anisotropy of the Ho spins, effectively acting as a two-dimensional spin ice. In this study, using a combination of magnetization, Hall conductivity measurements, and density functional theory calculations, we demonstrate how various spin-ice states, stabilized by external magnetic fields, influence the Fermi surface topology. More interestingly, we observe sharp transitions in Hall conductivity without concurrent changes in magnetization when an external magnetic field is applied along a particular crystallographic direction, underscoring the role of strong magnetic frustration and providing a new platform for exploring the interplay between magnetic frustration, electronic topology, and crystalline symmetry. These results also highlight the limitations of a simple spin-ice model, suggesting that a more sophisticated framework is necessary to capture the subtle experimental nuances observed.