Complex magnetic phase diagram and skyrmion lifetime in an ultrathin film from atomistic simulations

Rózsa, Levente; Simon, Eszter; Palotás, Krisztián; Udvardi, L.; Szunyogh, L.

doi:10.1103/physrevb.93.024417

Cited by 82 publications

(89 citation statements)

References 75 publications

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“…Moreover, it is known that the exchange coupling of Fe could be both ferromagnetic and antiferromagnetic which depends on the substrates' d-band filling. [42][43][44] Recently, ab initio calculation showed that ferromagnetic NN and AFM NNN interaction could coexist in multilayer Pt 1−x Ir x / Fe/Pd structures, 45 where our simulation results are promising and remain to be verified experimentally.…”

Section: B Hysteresis Loopmentioning

confidence: 73%

Skyrmions and multisublattice helical states in a frustrated chiral magnet

Yuan¹,

Gomonay²,

Kläui³

2017

Phys. Rev. B

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We investigate the existence and stability of skyrmions in a frustrated chiral ferromagnet by considering the competition between ferromagnetic (FM) nearest-neighbour (NN) interaction (J1) and antiferromagnetic (AFM) next-nearest-neighbour (NNN) interaction (J2). Contrary to the general wisdom that long-range ferromagnetic order is not energy preferable under frustration, the skyrmion lattice not only exists but is even stable for a large field range when J2 ≤ J1 compared with frustration-free systems. We defend that the enlargement of stability window of skyrmions is a consequence of the reduced effective exchange interaction caused by the frustration. A multi-sublattice helical state is found below the skyrmion phase, which results from the competition between AFM coupling that favors a two-sublattice Néel state and the chiral interaction that prefers a helix. As a byproduct, the hysteresis loop of the frustrated chiral system shrinks as the magnetization goes to zero and then opens up again, known as wasp-waist hysteresis loop. The critical field that separates the narrow and wide part of the wasp-waist loop depends exponentially on the strength of NNN coupling. By measuring the critical field, it is possible to determine the strength of NNN coupling.

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Section: B Hysteresis Loopmentioning

confidence: 73%

Skyrmions and multisublattice helical states in a frustrated chiral magnet

Yuan¹,

Gomonay²,

Kläui³

2017

Phys. Rev. B

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“…Skyrmions are also present in Fe (ultra-)thin-films, e.g., Fe monolayer on Ir(111) [20], Pd/Fe bilayer on Ir(111) [9,10,[30][31][32], 3 monolayers of Fe on Ir(111) [33] and Co ultrathin film Co/Ru(0001) [34]. In that case, magnetic interactions can be tuned by the choice of the magnetic film [35,36], the hybridization with the different substrates [11,35,37,38], or optional overlayers [9].…”

Section: Introductionmentioning

confidence: 99%

B–T phase diagram of Pd/Fe/Ir(111) computed with parallel tempering Monte Carlo

et al. 2018

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We use an atomistic spin model derived from density functional theory calculations for the ultra-thin film Pd/Fe/Ir(111) to show that temperature induces coexisting non-zero skyrmion and antiskyrmion densities. We apply the parallel tempering Monte Carlo method in order to reliably compute thermodynamical quantities and the B-T phase diagram in the presence of frustrated exchange interactions. We evaluate the critical temperatures using the topological susceptibility. We show that the critical temperatures depend on the magnetic field in contrast to previous work. In total, we identify five phases: spin spiral, skyrmion lattice, ferromagnetic phase, intermediate region with finite topological charge and paramagnetic phase. To explore the effect of frustrated exchange interactions, we calculate the B-T phase diagram, when only effective exchange parameters are taken into account.

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“…The question then arises as to how general this relation between skyrmion size and skyrmion stability is and whether it is possible to design an optimal medium where magnetic skyrmions are small enough while being sufficiently stable at ambient conditions. Equilibrium properties of skyrmions such as size and shape have intensively been studied since the very discovery of magnetic skyrmions more than twenty years ago [2][3][4][22][23][24][25][26], but quantitative characterization of skyrmion stability has started being addressed rather recently [27][28][29][30][31][32][33][34][35][36][37][38]. Thermal stability can be quantified by calculating skyrmion lifetime using harmonic transition state theory for spins [39].…”

Section: Introductionmentioning

confidence: 99%

Interplay between size and stability of magnetic skyrmions

Varentsova¹,

Potkina²,

Malottki³

et al. 2018

Nanosystems: Phys. Chem. Math.

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The relationship between the size and stability of isolated skyrmions in a magnetic monolayer is analyzed based on minimum energy path calculations and atomistic spin Hamiltonian. It is demonstrated that the energy barrier protecting the skyrmion from collapse to the ferromagnetic state is not uniquely defined by the skyrmion size, although these two properties as functions of relevant material parameters follow similar trends. Stability of nanoscale skyrmions can be enhanced by a concerted adjustment of material parameters. The proposed parameter transformation conserves the skyrmion size, but does not conserve the skyrmion shape which changes from an arrow-like pattern to a profile that resembles magnetic bubbles. This transformation of the skyrmion shape is accompanied by an increase in the collapse energy barrier and thus enhancement of skyrmion stability.

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Complex magnetic phase diagram and skyrmion lifetime in an ultrathin film from atomistic simulations

Cited by 82 publications

References 75 publications

Skyrmions and multisublattice helical states in a frustrated chiral magnet

Skyrmions and multisublattice helical states in a frustrated chiral magnet

B–T phase diagram of Pd/Fe/Ir(111) computed with parallel tempering Monte Carlo

Interplay between size and stability of magnetic skyrmions

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