Atomistic spin model based on a spin-cluster expansion technique: Application to the IrMn<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msub><mml:mrow /><mml:mrow><mml:mn>3</mml:mn></mml:mrow></mml:msub></mml:mrow></mml:math>/Co interface

Szunyogh, L.; Udvardi, L.; Jackson, J. M.; Nowak, Ulrich; Chantrell, R.W.

doi:10.1103/physrevb.83.024401

Cited by 69 publications

(89 citation statements)

References 38 publications

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“…(1) from the paramagnetic state. [25][26][27] Note that by using the SCE method no a priori information about the magnetic ground state is needed.…”

Section: Computational Detailsmentioning

confidence: 99%

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

et al. 2014

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We perform an extensive study of the spin-configurations in a PdFe bilayer on Ir(111) in terms of ab initio and spin-model calculations. We use the spin-cluster expansion technique to obtain spin model parameters, and solve the Landau-Lifshitz-Gilbert equations at zero temperature. In particular, we focus on effects of layer relaxations and the evolution of the magnetic ground state in external magnetic field. In the absence of magnetic field, we find a spin-spiral ground state, while applying external magnetic field skyrmions are generated in the system. Based on energy calculations of frozen spin configurations with varying magnetic field we obtain excellent agreement for the phase boundaries with available experiments. We find that the wave length of spin-spirals and the diameter of skyrmions decrease with increasing inward Fe layer relaxation which is correlated with the increasing ratio of the nearest neighbor Dzyaloshinskii-Moriya interaction and the isotropic exchange coupling, D/J. Our results also indicate that the applied field needed to stabilize the skyrmion lattice increases when the diameter of individual skyrmions decreases. Based on our observations, we suggest that the formation of the skyrmion lattice can be tuned by small structural modification of the thin film.

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“…(1) from the paramagnetic state. [25][26][27] Note that by using the SCE method no a priori information about the magnetic ground state is needed.…”

Section: Computational Detailsmentioning

confidence: 99%

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

et al. 2014

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“…Lately, the SCE method was combined with the relativistic disordered local moment (RDLM) scheme to determine the parameters of the spin Hamiltonian in Eq. (1) [5,13]. It should be noted that within the SCE-RDLM scheme the spin-spin correlations in the paramagnetic state of the system are calculated.…”

Section: Theory and Computational Detailsmentioning

confidence: 99%

“…In order to get a prediction about the magnetic ground state of the Fe ML we calculate first principles spin model parameters. To obtain the model parameters we use the spin-cluster expansion technique combined with the relativistic disordered local moment (RDLM) scheme [5,13]. We study the influence of the isotropic Heisenberg couplings on the magnetic ground state as well as the role of DzyaloshinskiiMoriya (DM) interactions representing a relativistic correction to the Heisenberg model.…”

Section: Introductionmentioning

confidence: 99%

Spin-correlations and magnetic structure in an Fe monolayer on 5dtransition metal surfaces

Simon¹,

Palotás²,

Újfalussy³

et al. 2014

J. Phys.: Condens. Matter

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Abstract. We present a detailed first principles study on the magnetic structure of an Fe monolayer on different surfaces of 5d transition metals. We use the spin-cluster expansion technique to obtain parameters of a spin model, and predict the possible magnetic ground state of the studied systems by employing the mean field approach and in certain cases by spin dynamics calculations. We point out that the number of shells considered for the isotropic exchange interactions plays a crucial role in the determination of the magnetic ground state. In the case of Ta substrate we demonstrate that the out-of-plane relaxation of the Fe monolayer causes a transition from ferromagnetic to antiferromagnetic ground state. We examine the relative magnitude of nearest neighbour Dzyaloshinskii-Moriya (D) and isotropic (J) exchange interactions in order to get insight into the nature of magnetic pattern formations. For the Fe/Os(0001) system we calculate a very large D/J ratio, correspondingly, a spin spiral ground state. We find that, mainly through the leading isotropic exchange and Dzyaloshinskii-Moriya interactions, the inward layer relaxation substantially influences the magnetic ordering of the Fe monolayer. For the Fe/Re(0001) system characterized by large antiferromagnetic interactions we also determine the chirality of the 120 • Néel-type ground state.PACS numbers: 75.10.Hk Spin-correlations and magnetic structure in an Fe monolayer on 5d transition metal surfaces2

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“…the biquadratic, 4-th order, or anisotropic exchange) can be also obtained in a systematic way either from the ferromagnetic ground state 27,28 or from the DLM state. 23 The second approach, which we follow in this work, is based on reciprocal-space calculation of spin-wave excitation energies by constraining the system to spin spirals of given wavevectors q. This requires non-collinear calculations, restricted to the primitive chemical unit cell (in the absence of spin-orbit coupling) by virtue of a generalized Bloch theorem.…”

Section: Introductionmentioning

confidence: 99%

“…17 It is widely used in methods where the Green function is available. 1,2,8,[18][19][20][21][22][23][24] A variant of this approach is the use of the disorder-local-moment (DLM) reference state 11 as an approximation to the magnetic disorder at the Curie temperature, from which one obtains exchange parameters 25,26 in a manner analogous to the method of infinitesimal rotations. 17 Higher-order interactions (e.g.…”

Section: Introductionmentioning

confidence: 99%

Exchange interactions and local-moment fluctuation corrections in ferromagnets at finite temperatures based on noncollinear density-functional calculations

et al. 2013

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We explore the derivation of interatomic exchange interactions in ferromagnets within density-functional theory (DFT) and the mapping of DFT results onto a spin Hamiltonian. We delve into the problem of systems comprising atoms with strong spontaneous moments together with atoms with weak induced moments. All moments are considered as degrees of freedom, with the strong moments thermally fluctuating only in angle and the weak moments thermally fluctuating in angle and magnitude. We argue that a quadratic dependence of the energy on the weak local moments magnitude, which is a good approximation in many cases, allows for an elimination of the weak-moment degrees of freedom from the thermodynamic expressions in favor of a renormalization of the Heisenberg interactions among the strong moments. We show that the renormalization is valid at all temperatures accounting for the thermal fluctuations and resulting in temperature-independent renormalized interactions. These are shown to be the ones directly derived from total-energy DFT calculations by constraining the strong-moment directions, as is done e.g. in spin-spiral methods. We furthermore prove that within this framework the thermodynamics of the weak-moment subsystem, and in particular all correlation functions, can be derived as polynomials of the correlation functions of the strong-moment subsystem with coefficients that depend on the spin susceptibility and that can be calculated within DFT. These conclusions are rigorous under certain physical assumptions on the measure in the magnetic phase space. We implement the scheme in the full-potential linearized augmented plane wave (FLAPW) method using the concept of spin-spiral states, considering applicable symmetry relations and the use of the magnetic force theorem. Our analytical results are corroborated by numerical calculations employing DFT and a Monte Carlo method.

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Atomistic spin model based on a spin-cluster expansion technique: Application to the IrMn3/Co interface

Cited by 69 publications

References 38 publications

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

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

Spin-correlations and magnetic structure in an Fe monolayer on 5dtransition metal surfaces

Exchange interactions and local-moment fluctuation corrections in ferromagnets at finite temperatures based on noncollinear density-functional calculations

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