Unlocking Bloch-type chirality in ultrathin magnets through uniaxial strain.

Gong Chen,Changyeon Won,Hee Young Kwon,Z Q Qiu,Sang Pyo Kang,Yizheng Wu,Andreas K Schmid,Alpha T N’Diaye

doi:10.1038/ncomms7598

Abstract

Chiral magnetic domain walls are of great interest because lifting the energetic degeneracy of left- and right-handed spin textures in magnetic domain walls enables fast current-driven domain wall propagation. Although two types of magnetic domain walls are known to exist in magnetic thin films, Bloch- and Néel-walls, up to now the stabilization of homochirality was restricted to Néel-type domain walls. Since the driving mechanism of thin-film magnetic chirality, the interfacial Dzyaloshinskii-Moriya interaction, is thought to vanish in Bloch-type walls, homochiral Bloch walls have remained elusive. Here we use real-space imaging of the spin texture in iron/nickel bilayers on tungsten to show that chiral domain walls of mixed Bloch-type and Néel-type can indeed be stabilized by adding uniaxial strain in the presence of interfacial Dzyaloshinskii-Moriya interaction. Our findings introduce Bloch-type chirality as a new spin texture, which may open up new opportunities to design spin-orbitronics devices.

Highlights

Chiral magnetic domain walls are of great interest because lifting the energetic degeneracy of left- and right-handed spin textures in magnetic domain walls enables fast current-driven domain wall propagation
In perpendicularly magnetized thin-film systems, domain walls (DWs) can be classified as two canonical types: in Bloch walls, the spin rotates like a helical spiral around an axis which is parallel or antiparallel to the DW normal, whereas in Neel walls the spin rotates like a cycloidal spiral
Our findings experimentally demonstrate the Bloch-type chirality as a new type of chiral spin texture stabilized by interfacial Dzyaloshinskii–Moriya interaction (DMI), which may open up new opportunities to design spin–orbitronics devices

Summary

Introduction

Chiral magnetic domain walls are of great interest because lifting the energetic degeneracy of left- and right-handed spin textures in magnetic domain walls enables fast current-driven domain wall propagation. Key points for these data demonstrated are as follows: when DW tangential direction is parallel to [1–10], that is, f 1⁄4 0°±3°, the histogram plotted in Fig. 2e shows that the angle a is scattered about a narrow distribution centred near 0°, confirming that these DWs are Neel type with left-handed chirality[17].

Results

Conclusion