First-principles investigation of the magnetic anisotropy and magnetic properties of Co/Ni(111) superlattices

Gimbert, Florian; Calmels, L.

doi:10.1103/physrevb.86.184407

Cited by 34 publications

(35 citation statements)

References 49 publications

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“…Seed layer impact on structural properties of [Co/Ni] To obtain large PMA in [Co/Ni] systems, highly textured, smooth fcc(111) films are required 24 . Fig.1 (Fig.3(a)), but both show clearly crystalline and texture matched.…”

Section: Resultsmentioning

confidence: 99%

Seed layer impact on structural and magnetic properties of [Co/Ni] multilayers with perpendicular magnetic anisotropy

Liu

Swerts

Devolder

et al. 2017

Journal of Applied Physics

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[Co/Ni] multilayers with perpendicular magnetic anisotropy (PMA) have been researched and applied in various spintronic applications. Typically the seed layer material is studied to provide the desired facecentered cubic (fcc) texture to the [Co/Ni] to obtain PMA. The integration of [Co/Ni] in back-end-of-line (BEOL) processes also requires the PMA to survive post-annealing. In this paper, the impact of NiCr, Pt, Ru, and Ta seed layers on the structural and magnetic properties of [Co(0.3 nm)/Ni(0.6 nm)] multilayers is investigated before and after annealing. The multilayers were deposited in-situ on different seeds via physical vapor deposition at room temperature. The as-deposited [Co/Ni] films show the required fcc(111) texture on all seeds, but PMA is only observed on Pt and Ru. In-plane magnetic anisotropy (IMA) is obtained on NiCr and Ta seeds, which is attributed to strain-induced PMA loss. PMA is maintained on all seeds after post-annealing up to 400 • C. The largest effective perpendicular anisotropy energy (K eff U ≈ 2 × 10 5 J/m 3 ) after annealing is achieved on NiCr seed. The evolution of PMA upon annealing cannot be explained by further crystallization during annealing or strain-induced PMA, nor can the observed magnetization loss and the increased damping after annealing. Here we identify the diffusion of the non-magnetic materials from the seed into [Co/Ni] as the major driver of the changes in the magnetic properties. By selecting the seed and post-annealing temperature, the [Co/Ni] can be tuned in a broad range for both PMA and damping.

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Section: Resultsmentioning

confidence: 99%

Seed layer impact on structural and magnetic properties of [Co/Ni] multilayers with perpendicular magnetic anisotropy

Liu

Swerts

Devolder

et al. 2017

Journal of Applied Physics

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“…So far, SOC in magnetic multilayers or superlattice has been studied intensively in terms of engineering the electronic structure in order to control the spontaneous magnetic anisotropy [3,5,6]. Here, we demonstrate the reverse process in a similarly anisotropic layered system Cr 1/3 NbS 2 , such that the spin polarization direction controlled by applied magnetic field alters the electronic structure via SOC.…”

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confidence: 86%

“…It has been shown that electronic structure can be altered via interface SOC by varying the superlattice structure, resulting in spontaneous magnetization perpendicular or parallel to the plane [5,6]. In lieu of magnetic thin films, we study the similarly anisotropic helimagnet Cr 1/3 NbS2, where the spin polarization direction, controlled by the applied magnetic field, can modify the electronic structure.…”

mentioning

confidence: 99%

Out-of-plane spin-orientation dependent magnetotransport properties in the anisotropic helimagnetCr1/3NbS2

et al. 2015

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Understanding the role of spin-orbit coupling (SOC) has been crucial to controlling magnetic anisotropy in magnetic multilayer films [1][2][3][4]. It has been shown that electronic structure can be altered via interface SOC by varying the superlattice structure, resulting in spontaneous magnetization perpendicular or parallel to the plane [5,6]. In lieu of magnetic thin films, we study the similarly anisotropic helimagnet Cr 1/3 NbS2, where the spin polarization direction, controlled by the applied magnetic field, can modify the electronic structure. As a result, the direction of spin polarization can modulate the density of states, and in turn affect the in-plane electrical conductivity. In Cr 1/3 NbS2, we found an enhancement of in-plane conductivity when the spin polarization is out-of-plane, as compared to in-plane spin polarization. This is consistent with the increase of density of states near the Fermi energy at the same spin configuration, found from first principles calculations. We also observe unusual field dependence of the Hall signal in the same temperature range. This is unlikely to originate from the non-collinear spin texture, but rather further indicates strong dependence of electronic structure on spin orientation relative to the plane. PACS numbers:Despite the fact that its typical energy scale in 3d ferromagnetic metals is small compared to other relevant scales such as band widths, SOC mixes the nature of the spin and orbital components of the Bloch state in a nontrivial way and leads to a variety of electrical transport phenomena e.g. the anomalous Hall effect (AHE), anisotropic magnetoresistance (AMR), and the planar Hall effect. In addition, the recent work in non-collinear magnetically ordered states and the related topological Hall effect [7][8][9] not only has renewed the pivotal role of SOC through the Dzyaloshinskii-Moriya (DM) interaction [10][11][12], but also has presented a possibility to employ these findings for functional components in magnetic devices [13,14]. Non-collinear magnetic ordering is also suggested to possibly manifest spin-orbit coupling in a complex manner, through the DM interaction [12,15,16]. Consequently, the modification of electronic structure by spin-orbit coupling is expected to make in-plane electrical transport sensitive to the magnetization orientation relative to the plane.Cr 1/3 NbS 2 has a layered crystalline structure, in which 3d transition metal Cr atoms are intercalated in the hexagonal 2H-type NbS 2 matrix as trivalent ions and magnetically order at T C = 133 K. The ferromagnetic layers of Cr 3+ lie coplanar with the crystallographic abplanes and the magnetic helix propagates along the caxis with a long pitch of 48 nm, corresponding to 40 unit cells [17]. Its helimagnetic ordering is attributed to the DM interaction, which originates from a broken inversion symmetry shared by all members of space group P 6 3 22 [17][18][19].

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“…We used E max =100 Ry, meaning that all eigen-states were included. Even though the formula was originally derived for systems with only one atomic type, the relation between the MCA energy and the anisotropy of orbital magnetic moments has been frequently applied also for multicomponent systems [12,[53][54][55][56][57]. In such a case an estimate of E MCA can be made by evaluating (cf.…”

Section: B Magneto-crystalline Anisotropy Energymentioning

confidence: 99%

Magnetocrystalline anisotropy of FePt: A detailed view

Khan¹,

Blaha²,

Ebert³

et al. 2016

Phys. Rev. B

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To get a reliable ab-initio value for the magneto-crystalline anisotropy (MCA) energy of FePt, we employ the full-potential linearized augmented plane wave (FLAPW) method and the full-potential Korringa-Kohn-Rostoker (KKR) Green function method. The MCA energies calculated by both methods are in a good agreement with each other. As the calculated MCA energy significantly differs from experiment, it is clear that many-body effects beyond the local density approximation are essential. It is not really important whether relativistic effects for FePt are accounted for by solving the full Dirac equation or whether the spin-orbit coupling (SOC) is treated as a correction to the scalar-relativistic Hamiltonian. From the analysis of the dependence of the MCA energy on the magnetization angle and on the SOC strength it follows that the main mechanism of MCA in FePt can be described within second order perturbation theory. However, a distinct contribution not accountable for by second order perturbation theory is present as well.

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First-principles investigation of the magnetic anisotropy and magnetic properties of Co/Ni(111) superlattices

Cited by 34 publications

References 49 publications

Seed layer impact on structural and magnetic properties of [Co/Ni] multilayers with perpendicular magnetic anisotropy

Seed layer impact on structural and magnetic properties of [Co/Ni] multilayers with perpendicular magnetic anisotropy

Out-of-plane spin-orientation dependent magnetotransport properties in the anisotropic helimagnetCr1/3NbS2

Magnetocrystalline anisotropy of FePt: A detailed view

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