Local spin-flip transitions induced by magnetic quantum impurities in two-dimensional magnets

TL;DR

This paper predicts a universal local spin-flip transition mechanism caused by magnetic impurities in 2D quantum magnets, linked to magnon bound state crossings, with potential detection via scanning tunneling spectroscopy.

Contribution

It introduces a general spin-flip transition mechanism in 2D magnets caused by impurities, applicable without conservation laws, and demonstrates its detection in specific materials.

Findings

Spin-flip transitions occur when magnon bound states cross zero energy.

The mechanism applies to 2D van der Waals magnets like CrI3 and α-RuCl3.

Detection methods include scanning tunneling spectroscopy.

Abstract

We predict a general local spin-flip transition mechanism caused by magnetic quantum impurities in (partially) polarized phases of quantum magnets in the absence of conservation laws. This transition arises when a magnon bound state crosses zero energy as function of the magnetic field. As application, we study 2D van der Waals magnets described by the Kitaev-Heisenberg honeycomb model which applies to the transition metal trihalides CrI$_3$ and $\alpha$-RuCl$_3$. We consider adatom and substitutional impurity positions, and show how spin-flip transitions can be detected in scanning tunneling spectroscopy.