Ternary superlattice boosting interface-stabilized magnetic chirality

Abstract

In cobalt-nickel multilayers grown on iridium surfaces, magnetic homo-chirality can be stabilized by Dzyaloshinskii-Moriya interactions (DMI) at the interface with the substrate. When thickness of the multilayers is increased beyond threshold values, then non-chiral bulk properties exceed interface contributions and this type of chirality vanishes. Here, we use spin-polarized low energy electron microscopy to measure these thickness thresholds, and we determine estimates of the strength of the DMI from the measurements. Even though the same 5d heavy metal is used as a substrate, a remarkably large variation is found between the two 3d magnets: our results indicate that the strength of the DMI at Co/Ir interfaces is three times larger than at Ni/Ir interfaces. We show how this finding provides ways to extend interfacial-DMI stabilization of domain wall chirality to 3d/5d/3d ternary multilayers such as [Ni/Ir/Co]n. Such strategies may extend chirality-control to larger film thickness and a wider range of substrates, which may be useful for designing new spintronics devices.

Room temperature skyrmion ground state stabilized through interlayer exchange coupling

“…The histogram shows that measurements of the angle a are strongly peaked at 180 , confirming the qualitative designation of these features as right-handed N eel-type. [38][39][40] The analysis of images of several samples (not shown) corroborates that this right-handed N eel-texture is a reproducible feature of the Fe/Ni/Cu/Ni/Cu(001) system.…”

“…After completion of Fe/Ni/Cu/Ni/ Cu(001) multilayers, spin textures were measured by imaging components of the magnetization vector along Cartesian x, y, z directions at room temperature. 33,[38][39][40] Figure 1 illustrates our approach to stabilize a magnetic skyrmion ground state. Grown directly on a Cu(001) single crystal, the magnetic structure of Fe/Ni bilayer films exhibits a chiral stripe domain phase, this is indicated by red/blue stripes in the sketch in Fig.…”

“…[38][39][40] We can start by defining equatorial lines for each skyrmion as the lines circling around the skyrmion cores where the magnetization is fully in-plane (i.e., where the out-of plane component of m vanishes). In each pixel on these skyrmion equators, we measure the in-plane orientation of the magnetization vector m and the orientation of the normal vector n of the skyrmion equator (to avoid ambiguity, we define n to point away from the skyrmion cores).…”

Imaging and Tailoring the Chirality of Domain Walls in Magnetic Films

“…While the phase diagram shows that the stability of left-handed chiral Néel domain walls in [Co/Ni] n multilayers grown on iridium is limited to a narrow thickness range (the red region in Figure 4 f [ 26 ] Finally, we note that theoretical simulations based on a Monte Carlo model successfully predict the experimental phase diagram, suggesting that a wealth of possibilities to engineer domain-wall types with controlled chirality can be achieved by extending the choices of materials beyond the handful of elements used in this study. [ 23 ] …”

Magnetic stripe domains of [Pt/Co/Cu]10 multilayer near spin reorientation transition

“…[16][17][18] Moreover, micromagnetic simulations 19 suggest that skyrmions induced by interfacial DMI can be manipulated efficiently by low-density charge currents, which can open a door to room temperature skyrmion-based spintronics. However, experimentally the skyrmion was only observed in very few thin-film stacks, [20][21][22][23] and no topological Hall effect has been distinguished in those systems. Thus, it is essential to explore more magnetic heterostructures with the broken inversion symmetry for searching high density skyrmions in robust thin-film heterostructures.…”