Local Probes for Charge-Neutral Edge States in Two-Dimensional Quantum Magnets

April 21 2021 (Wed.) at 3:00PM (EST)

Willian Natori
Institut Laue Langevin

The most general signatures of topological states of matter are emergent edge states due to the bulk-boundary correspondence. Rapid progress was made in the experimental research of charged topological phases due to surface-sensitive probes. However, direct observation of topological surface states is more challenging in quantum magnets because of the excitations' charge-neutral character. The need for such experimental settings has become more pressing due to the necessity of correctly diagnosing quantum spin liquid in compounds such as RuCl3 under moderate magnetic fields.

In this talk, we propose spin-polarized scanning tunneling microscopy as a spin-sensitive local probe to edge states in topological magnets. We show how the tunneling conductance is directly related to the local dynamical structure factor and the relative spin polarization of the metallic substrate and the microscope tip. In particular, we determine the expected tunneling conductance of the Kitaev honeycomb model with open boundaries. In doing so, we describe how such an experiment would probe the hypothesized quantum spin liquid in RuCl3.