Tailoring magnetic skyrmions in ultra-thin transition metal films

Abstract

Skyrmions in magnetic materials offer attractive perspectives for future spintronic applications since they are topologically stabilized spin structures on the nanometre scale, which can be manipulated with electric current densities that are by orders of magnitude lower than those required for moving domain walls. So far, they were restricted to bulk magnets with a particular chiral crystal symmetry greatly limiting the number of available systems and the adjustability of their properties. Recently, it has been experimentally discovered that magnetic skyrmion phases can also occur in ultra-thin transition metal films at surfaces. Here we present an understanding of skyrmions in such systems based on first-principles electronic structure theory. We demonstrate that the properties of magnetic skyrmions at transition metal interfaces such as their diameter and their stability can be tuned by the structure and composition of the interface and that a description beyond a micromagnetic model is required in such systems.

New Type of Stable Particlelike States in Chiral Magnets

“…1 are consistent with the continuum theory [18] and experimental data on the direct observation of SkL in thin films of cubic helimagnetic alloys as Fe 1−x Co x Si [11], Mn 1−x Fe x Ge [9], Mn 1−x Fe x Si [19] and pure MnSi [20] and FeGe [21]. The mechanism of SkL stabilization in thin films of cubic helimagnet differs from two-dimensional systems with interface induced DMI [22] and anisotropic bulk helimagnets [23,24]. According to Ref.…”

Formation of magnetic skyrmions with tunable properties in PdFe bilayer deposited on Ir(111)

“…This finding suggests that the skyrmion lattice above about 3 T is metastable. It should be noted that Dupé et al 15 found magnetic phase transitions at much larger external fields as compared to the experiments.…”

“…This does not contradict to the observed strong relationship between the SS wave length and the ratio of nearest neighbor parameters, D/J, as it just highlights that further DM interactions are needed to decrease the energy of the spin-spiral below that of the FM state. Without DM interactions the magnetic ground state was ferromagnetic, in contrast to Dupé et al 15 who obtained SS ground state by neglecting spin-orbit interaction in their calculations.…”

“…[13][14][15]27,36 In Fig. 2 the magnitudes of the DM vectors between the Fe atoms are shown as a function of the inter-atomic distance for all considered layer relaxations.…”

Formation and stability of metastable skyrmionic spin structures with various topologies in an ultrathin film

“…The skyrmion lattice phase was first identified in MnSi [19], and later in other bulk materials belonging to certain symmetry classes [20][21][22][23][24][25][26]. While the skyrmion lattice is a thermodynamic phase [27][28][29], skyrmions * rozsa.levente@wigner.mta.hu may also appear as metastable localized spin configurations on the collinear background [30], and most suggested future applications rely on such individual or isolated skyrmions [4][5][6]. The presence of individual skyrmions has been demonstrated in several ultrathin and multilayer films [31][32][33] by combining magnetic transition metals with heavy nonmagnetic elements, which provides a way of enhancing the Dzyaloshinsky-Moriya interaction [34,35].…”