Guiding Spin Spirals by Local Uniaxial Strain Relief

Abstract

We report on the influence of uniaxial strain relief on the spin spiral state in the Fe double layer grown on Ir(111). Scanning tunneling microscopy (STM) measurements reveal areas with reconstruction lines resulting from uniaxial strain relief due to the lattice mismatch of Fe and Ir atoms, as well as pseudomorphic strained areas. Magnetic field-dependent spin-polarized STM measurements of the reconstructed Fe double layer reveal cycloidal spin spirals with a period on the nm scale. Globally, the spin spiral wave fronts are guided along symmetry-equivalent [112̅] crystallographic directions of the fcc(111) substrate. On an atomic scale the spin spiral propagation direction is linked to the [001] direction of the bcc(110)-like Fe, leading to a zigzag shaped wave front. The isotropically strained pseudomorphic areas also exhibit a preferred magnetic periodicity on the nm scale but no long-range order. We find that already for local strain relief with a single set of reconstruction lines a strict guiding of the spin spiral is realized.

Electric-field-driven switching of individual magnetic skyrmions

“…For the growth of Fe on Ir(111) a transition from pseudomorphic atom arrangement for the Fe monolayer (ML) to more bcc(110)-like Fe areas for higher layers is expected. A structure model that is in agreement with the experimentally observed symmetries is shown: the ML-Fe grows pseudomorphic to Ir(111) in fcc stacking, and for higher layers a uniaxial compression along the closed-packed atomic row leads to dislocation lines running along (22). Locally the atomic arrangement varies periodically from fcc via bcc-like to hcp and further via bcc-like to fcc; two bcc(110) unit cells are indicated by rectangles.…”

Tailoring noncollinear magnetism by misfit dislocation lines

“…The wavelength of the spirals is smaller in the double line regions (3 nm to 4.5 nm) than in the single line regions (between 5 nm and 10 nm). Furthermore, the wavefront of the double line spirals has a zigzag shape 9,10 , whereas that of the spirals in the single line regions is straight but tilted with respect to the lines as can be seen from the details of spin-resolved differential conductance maps in Fig. 2(c) and Fig.…”

“…2(e). The proposed structure models can explain these shapes for the wavefronts: the wavevector prefers to follow the bcc[001]-like rows of atoms as observed for the double layer Fe on Ir(111) 10 , Cu(111) 12 and W(110) 13 . For the double lines, the direction of the rows alternate and this creates the magnetic zigzag structure, whereas the direction does not change for the single lines, as shown by the bcc(110)-like unit cells marked in red in Fig.…”

Nanoscale magnetic skyrmions in metallic films and multilayers: a new twist for spintronics

“…The lack of inversion symmetry at interfaces gives rise to interfacial DM interactions [15][16][17][18][19][20][21][22][23] , which favour the formation of non-collinear spin textures with a unique rotational sense in ultrathin magnetic films that are in contact with materials that exhibit a large spin-orbit coupling (BOX 2). Examples of such interface-stabilized spin configurations include chiral magnetic domain walls [37][38][39][40][41][42][43][44] , cycloidal [45][46][47][48][49][50][51] and conical spin spirals 52 , and chiral skyrmion lattices 13,[53][54][55][56] . These non-collinear spin states became accessible for atomic-scale studies thanks to the development of SP-STM 25,57 .…”