Interfacial Dzyaloshinskii-Moriya interaction and orbital magnetic moments of metallic multilayer films

Yamamoto, Keiji; Pradipto, Abdul‐Muizz; Nawa, Kenji; Akiyama, Toru; T, Ito; Ono, Teruo; Nakamura, Kohji

doi:10.1063/1.4973217

Cited by 22 publications

(19 citation statements)

References 23 publications

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“…But the Ir/FM case is not as straightforward as Pt/FM interface. Initially, ab initio calculations proposed that Ir introduces the opposite chirality to Pt 34,35,62 , which was supported by various experimental reports of additive effects 17,36,59,63,64 . Later on, the sign of DMI for Ir was debated when several experimental studies observed right-handed chirality in multilayers including Ir/Co 29,38,60 .…”

Section: Discussionmentioning

confidence: 83%

Domain-wall motion and interfacial Dzyaloshinskii-Moriya interactions inPt/Co/Ir(tIr)/Tamultilayers

et al. 2019

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The interfacial Dzyaloshinskii-Moriya interaction (DMI) is important for chiral domain walls (DWs) and for stabilizing magnetic skyrmions. We study the effects of introducing increasing thicknesses of Ir, from zero to 2 nm, into a Pt/Co/Ta multilayer between the Co and Ta. We observe a marked increase in magnetic moment, due to the suppression of the dead layer at the interface with Ta, but the perpendicular anisotropy is hardly affected. All samples show a universal scaling of the field-driven domain wall velocity across the creep and depinning regimes. Asymmetric bubble expansion shows that DWs in all of the samples have the left-handed Néel form. The value of in-plane field at which the creep velocity shows a minimum drops markedly on the introduction of Ir, as does the frequency shift of the Stokes and anti-Stokes peaks in Brillouin light scattering measurements. Despite this qualitative similarity, there are quantitative differences in the DMI strength given by the two measurements, with BLS often returning higher values. Many features in bubble expansion velocity curves do not fit simple models commonly used to date, namely a lack of symmetry about the velocity minimum and no difference in velocities at high in-plane field. These features are explained by the use of a model in which the depinning field is allowed to vary with in-plane field in a way determined from micromagnetic simulations. This theory shows that velocity minimum underestimates the DMI field, consistent with BLS returning higher values. Our results suggest that the DMI at an Ir/Co interface has the same sign as the DMI at a Pt/Co interface.

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Section: Discussionmentioning

confidence: 83%

Domain-wall motion and interfacial Dzyaloshinskii-Moriya interactions inPt/Co/Ir(tIr)/Tamultilayers

et al. 2019

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“…However, the orbital hybridization between the spin–orbit coupled ions and the magnetic matrix was explicitly neglected in the theory, which becomes problematic when considering transition metal interfaces. On the other hand, theories have predicted that SOC combined with inversion symmetry breaking (ISB) naturally introduces a chirality to conduction electron spins in equilibrium and the interfacial DMI at an FM/HM interface is related to this spin chirality 16 – 20 . It has also been reported that the spin chirality is a manifestation of the chirality of the orbital magnetism in strongly spin–orbit coupled systems with ISB 21 , 22 .…”

Section: Introductionmentioning

confidence: 99%

Correlation of the Dzyaloshinskii–Moriya interaction with Heisenberg exchange and orbital asphericity

Kim

Ueda

et al. 2018

Nat Commun

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Chiral spin textures of a ferromagnetic layer in contact to a heavy non-magnetic metal, such as Néel-type domain walls and skyrmions, have been studied intensively because of their potential for future nanomagnetic devices. The Dyzaloshinskii–Moriya interaction (DMI) is an essential phenomenon for the formation of such chiral spin textures. In spite of recent theoretical progress aiming at understanding the microscopic origin of the DMI, an experimental investigation unravelling the physics at stake is still required. Here we experimentally demonstrate the close correlation of the DMI with the anisotropy of the orbital magnetic moment and with the magnetic dipole moment of the ferromagnetic metal in addition to Heisenberg exchange. The density functional theory and the tight-binding model calculations reveal that inversion symmetry breaking with spin–orbit coupling gives rise to the orbital-related correlation. Our study provides the experimental connection between the orbital physics and the spin–orbit-related phenomena, such as DMI.

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“…It is now understood that the interfacial DM interaction plays a role in the domain-wall energy in perpendicular anisotropy thin films with broken inversion symmetry [6][7][8]. The DM interactions at Pt/Co and Ir/Co interfaces are generally held to be of opposite sign [9,10], so are expected to contribute to a large net DM interaction when combined in an asymmetric trilayer such as Pt/Co/Ir. These trilayers are the building blocks of multilayers where skyrmionic structures have been detected [11], making the understanding of their properties key to the development of devices based on the control and motion of chiral spin structures.…”

Section: Introductionmentioning

confidence: 99%

Magnetic properties, domain-wall creep motion, and the Dzyaloshinskii-Moriya interaction in Pt/Co/Ir thin films

et al. 2018

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We study the magnetic properties of perpendicularly magnetized Pt/Co/Ir thin films and investigate the domain-wall creep method of determining the interfacial Dzyaloshinskii-Moriya (DM) interaction in ultrathin films. Measurements of the Co layer thickness dependence of saturation magnetization, perpendicular magnetic anisotropy, and symmetric and antisymmetric (i.e., DM) exchange energies in Pt/Co/Ir thin films have been made to determine the relationship between these properties. We discuss the measurement of the DM interaction by the expansion of a reverse domain in the domain-wall creep regime. We show how the creep parameters behave as a function of in-plane bias field and discuss the effects of domain-wall roughness on the measurement of the DM interaction by domain expansion. Whereas modifications to the creep law with DM field and in-plane bias fields have taken into account changes in the energy barrier scaling parameter α, we find that both α and the velocity scaling parameter v 0 change as a function of in-plane bias field.

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Interfacial Dzyaloshinskii-Moriya interaction and orbital magnetic moments of metallic multilayer films

Cited by 22 publications

References 23 publications

Domain-wall motion and interfacial Dzyaloshinskii-Moriya interactions inPt/Co/Ir(tIr)/Tamultilayers

Domain-wall motion and interfacial Dzyaloshinskii-Moriya interactions inPt/Co/Ir(tIr)/Tamultilayers

Correlation of the Dzyaloshinskii–Moriya interaction with Heisenberg exchange and orbital asphericity

Magnetic properties, domain-wall creep motion, and the Dzyaloshinskii-Moriya interaction in Pt/Co/Ir thin films

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