Comment on Proper and improper chiral magnetic interactions

In a recent paper by dos Santos Dias et al. [Phys. Rev. B 103, L140408 (2021)], a critique of earlier works analyzing low-energy spin Hamiltonians is put forth. To be precise, it is the large noncollinear contributions to the Dzyaloshinskii-Moriya interaction (DMI) that is the main concern of dos Santos Dias et al. In this Comment, we clarify the microscopic mechanisms for the large DMI that can be found in noncollinear magnets. Furthermore, we outline the complementary nature of the different parametrizations of a spin Hamiltonian, with strengths and weaknesses of both approaches. Specifically, we stress the physical insight in the interpretation of the DMI, when decomposed in microscopic electron and spin densities and currents.

Automated summary

This paper critiques earlier works on analyzing low-energy spin Hamiltonians and focuses on the large noncollinear contributions to the Dzyaloshinskii-Moriya interaction (DMI). It clarifies the microscopic mechanisms for the large DMI in noncollinear magnets and outlines the complementary nature of different parametrizations of a spin Hamiltonian.