Skyrmions in square-lattice antiferromagnets

Abstract

The ground states of square-lattice two-dimensional antiferromagnets with anisotropy in an external magnetic field are determined using Monte Carlo simulations and compared to theoretical analysis. We find a phase in between the spin-flop and spiral phase that shows strong similarity to skyrmions in ferromagnetic thin films. We show that this phase arises as a result of the competition between Zeeman and Dzyaloshinskii-Moriya interaction energies of the magnetic system. Moreover, we find that isolated (anti-)skyrmions are stabilized in finite-sized systems, even at higher temperatures. The existence of thermodynamically stable skyrmions in square-lattice antiferromagnets provides an appealing alternative over skyrmions in ferromagnets as data carriers.

Skyrmions in antiferromagnets: Thermal stability and the effect of external field and impurities

“…The effect of an external magnetic field on the transformation between a skyrmion in FM and a skyrmion in AFM has been presented on the basis of a continuum model. 25 Denoting by L the staggered magnetization and by M the total magnetization, the energy density ω(r) for AFM can be written as…”

“…19,20 Skyrmion-like objects in continuum models were also predicted in a certain subclass of antiferromagnetic materials. 21 More recently, theoretical analysis of skyrmions in a continuum representation of an AFM material has been presented by Keesman et al 25 The ground state was determined using Monte Carlo simulations and the results compared to theoretical analysis. For finite systems, a phase that shows similarities with skyrmions was identified in between the spin flop and the spiral phases.…”

Antiferromagnetism Emerging in a Ferromagnet with Gain

“…Compared to their FM counterparts, AFM skyrmions [47] have some other advantages, such as the elevated mobility [48][49][50][51] and the unusual thermal properties [48,52], among others [53][54][55][56][57]. One recent breakthrough toward this direction is the experimental realization of ferrimagnetic skyrmions in GdFeCo films with inhibited skyrmion Hall effect [58,59].…”

Skyrmion Crystals in Frustrated Shastry–Sutherland Magnets

“…First, the effect of the exchange frustration on the stabilization of skyrmions at a low temperature T = 0.01 is investigated. Without the loss of generality, we fixed FM J 2 = 0.5 and D = 0.73 consistent with the earlier work, and modulated the frustration by introducing AFM couplings J 1 = 2 J 3 = − α . Here, the ratio of D to J 2 is chosen to be the same as in the square lattice system to help one understand the frustration effect easier, and other values hardly change our main conclusions.…”

“…Most recently, the 2 q phase is observed in the square‐lattice antiferromagnets, which shows strong similarity to skyrmions in FM films. In this part, we investigated the field‐induced spin orders for AFM J 2 and paid particular attention to the effect of J 2 on the low T phase diagram.…”