Experimental verification of the rotational sense and type of chiral spin spiral structure by spin-polarized scanning tunneling microscopy

TL;DR

This study experimentally confirms the in-plane rotational sense and type of a chiral spin spiral in a Mn monolayer on W(110) using spin-polarized STM, aligning with theoretical predictions and highlighting substrate influence on Dzyaloshinskii--Moriya interaction polarity.

Contribution

First experimental verification of the rotational sense and type of a chiral spin spiral in a Mn monolayer on W(110) using spin-polarized STM, confirming theoretical predictions.

Findings

Spin spiral rotates in the plane.

Rotational sense is left-handed.

Substrate determines Dzyaloshinskii--Moriya interaction polarity.

Abstract

We report on experimental verification of the rotational sense and type of homogeneous chiral spin spiral order in a Mn monolayer on a W(110) substrate using spin-polarized scanning tunneling microscopy. We found that the magnetic contrast due to the spin spiral order almost vanishes with a magnetic tip magnetized normal to the (001) plane, indicating that the spin spiral rotates in the plane. From a shift in the most-contrasted sites by changing the tip magnetization direction within the rotating plane, we reveal that the rotational sense is left-handed, consistent with the previous results predicted by first-principle calculations. By comparing the current system with a chiral magnetic domain wall in Fe double layers on the same substrate, we found that the polarity of the Dzyaloshinskii--Moriya interaction, the driving force of those chiral magnets, is dominantly determined by the choice of the substrate rather than the overlayer.