Local excitation of kagome spin ice magnetism in HoAgGe seen by scanning tunneling microscopy

TL;DR

This study uses scanning tunneling microscopy to observe local spin excitations in kagome spin ice HoAgGe, revealing inelastic tunneling signals linked to spin ice magnetism and demonstrating local magnetic excitations influenced by spin-orbit coupling.

Contribution

It introduces a novel inelastic tunneling technique to probe local spin excitations in kagome spin ice HoAgGe, providing new insights into its magnetic properties.

Findings

Detected inelastic tunneling dips related to spin ice magnetism.

Signal disappears above the spin ice transition temperature.

Model explains spin-flip processes considering spin-orbit coupling.

Abstract

The kagome spin ice can host frustrated magnetic excitations by flipping its local spin. Under an inelastic tunneling condition, the tip in a scanning tunneling microscope can flip the local spin, and we apply this technique to kagome metal HoAgGe with a long-range ordered spin ice ground state. Away from defects, we discover a pair of pronounced dips in the local tunneling spectrum at symmetrical bias voltages with negative intensity values, serving as a striking inelastic tunneling signal. This signal disappears above the spin ice formation temperature and has a dependence on the magnetic fields, demonstrating its intimate relation with the spin ice magnetism. We provide a two-level spin-flip model to explain the tunneling dips considering the spin ice magnetism under spin-orbit coupling. Our results uncover a local emergent excitation of spin ice magnetism in a kagome metal, suggesting that local electrical field induced spin flip climbs over a barrier caused by spin-orbital locking.