Creation and Annihilation of Skyrmions in the Frustrated Magnets with Competing Exchange Interactions

Abstract

In triangular-lattice magnets, the coexistence of third-neighbor antiferromagnetic and nearest-neighbor ferromagnetic exchange interactions can induce rich magnetic phases including noncoplanar skyrmion crystals. Based on Monte Carlo simulation, we studied the dependence of magnetic phase transition on exchange interaction strength. Under the consideration of uniaxial anisotropy and magnetic field both perpendicular to the film plane, a large antiferromagnetic exchange interaction induces a high frustration. When the value of antiferromagnetic exchange interaction is one and a half times larger than the ferromagnetic one, a magnetic phase composed of canting spin stripes, never observed in the chiral magnets, forms. Interestingly, different canting spin stripes along three 120 degree propagation directions may coexist randomly in a magnetic phase, attesting that the canting spin stripes are three-fold degenerate states akin to helices and the multiple state of canting spin stripes is a circular configuration with zero skyrmion charge number. Moreover, skyrmions and antiskyrmions can be observed simultaneously in the configuration at the low temperature nearly close to 0 K, and their configuration and diameter properties are discussed. Finally, the mechanisms of skyrmion creation and annihilation are properly interpreted by comparing exchange and Zeeman energy terms.

Controlling the helicity of magnetic skyrmions by electrical field in frustrated magnets

“…For the frustrated triangular model with J 1 -J 2 or J 1 -J 3 , rich phase diagrams have been reported [53,54,61,66]. Fig.…”

“…For the frustrated triangular model with J 1 -J 2 or J 1 -J 3 , rich phase diagrams have been reported [53,54,61,66]. Under the consideration of uniaxial anisotropy and magnetic field both perpendicular to the lattice plane (e k and e h along +z direction), the perpendicularly magnetized (PM) skyrmion crystal emerges at intermediate h and above a small k, and remains down to zero-temperature.…”

Spin textures induced by quenched disorder in a reentrant spin glass: Vortices versus “frustrated” skyrmions

“…SKs form double-twist solitonic structures, offering many perspectives in spintronics and data storage [27,28]. As predicted by theory [29][30][31][32][33], some anisotropic ordered magnets with competing nearest neighbor (NN) and next nearest neighbor (NNN) exchange interactions may host localized SKs with versatile internal structure and smooth rotation of the magnetization. Different types of modulated phases such as hexagonal or square SK lattices have been predicted, yielding a very rich phase diagram [30].…”

Trochoidal motion and pair generation in skyrmion and antiskyrmion dynamics under spin–orbit torques

“…This allows individual skyrmions to exist as metastable states, which has been brought to light in recent experiments [26]. Moreover, it has been shown that a variety of antiskyrmion states (q = −1, −2) are also metastable when frustrated exchange interactions are taken into account in such ultrathin films [27][28][29][30] and more generally in bulk chiral magnets [31,32], which lead to an attractive interaction between skyrmions [33]. We employed density-functional theory calculations to obtain estimates of the exchange, anisotropy, and DMI energies for PdFe/Ir(111), which were then used to parametrise an atomistic spin model for studying the dynamics (see Methods).…”