Proximity-induced magnetism and the enhancement of damping in ferromagnetic/heavy metal systems

Swindells, C.; Głowiński, Hubert; Choi, Y.; Haskel, D.; Michałowski, Paweł Piotr; Hase, Thomas P. A.; Kuświk, Piotr; Atkinson, D.

doi:10.1063/5.0064336

Cited by 11 publications

(6 citation statements)

References 57 publications

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“…For Pt, λ sd is of the order of several nanometers [6,47,56], so the first few nanometers of Pt are most important for spin current decay. The second length scale is the extent of the interfacial PIM, which, as shown earlier, at around 2 nm is shorter than the spin diffusion length, but is positively related with enhancement of the damping [10]. The third factor is the role of the Cu layer and the associated interfaces with respect to spin current propagation.…”

Section: B Separating the Effects Of Pt Pim And The Cu Sl Interface E...mentioning

confidence: 79%

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Magnetic damping in ferromagnetic/heavy-metal systems: The role of interfaces and the relation to proximity-induced magnetism

et al. 2022

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Damping and spin transport in spintronic multilayered systems continues to be a topic of active research. The enhancement of damping in ferromagnet(FM)/spacer layer (SL)/heavy metal (HM) thin-film systems was studied for Co25Fe75/SL/Pt with a non-magnetic (NM) SL of either Au or Cu with variable thickness, in order to understand the correlation with proximity induced magnetism (PIM) in the HM. Structural, PIM and magnetic damping measurements were undertaken on the same samples. Specifically, secondary ion mass spectroscopy (SIMS), element specific X-ray magnetic reflectivity and X-ray magnetic circular dichroism (XRMR, XMCD) at the Pt and Au L3 edges, and ferromagnetic resonance (FMR) methods were used. With increasing thickness of a Cu or Au SL directly between the FM and the Pt layer, the Pt PIM and the damping both fall rapidly, with a relationship between damping and PIM that depends on the SL material. The PIM observed in the Au layer showed a complex dependence on the layer thickness, suggesting some hybridisation with the Pt. The role of the number and location of interfaces on the damping was demonstrated with the addition of a SL within the Pt layer, which showed that the specific details of the NM/HM interface also affects the damping. The insertion of a Cu SL within the Pt showed a measurable increase in the overall enhancement of the damping while the insertion of a Au SL into Pt had almost no effect on the damping. Together these results demonstrate the role of both PIM and of additional interfaces in the enhancement of damping in FM/HM systems, which is not fully accounted for by existing theory.

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Section: B Separating the Effects Of Pt Pim And The Cu Sl Interface E...mentioning

confidence: 79%

“…Such interfacial spin transport depends critically upon the details of the interface [1][2][3][4][5][6], but there are questions about its dependence on the location and number of interfaces. Furthermore, the role of the proximity induced moment (PIM) of the HM on damping and spin transport has been a subject of debate [7][8][9][10].…”

Section: Introductionmentioning

confidence: 99%

Magnetic damping in ferromagnetic/heavy-metal systems: The role of interfaces and the relation to proximity-induced magnetism

et al. 2022

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“…The results show a strong correlation between the enhancement of the damping and the magnitude of the Pt PIM, with the damping falling toward the bulk uncapped FM values when the Pt PIM is lost. 74 The two FM systems presented showed different structural behavior with the Pt PIM in CoFe/Au/Pt being closely associated with the FM/Pt interface, while in the NiFe/Au/Pt system, the Pt PIM extends further into the Pt layer due to some diffusion of the Ni into Au and Pt. The relationship between Pt PIM and damping was further evidenced in a system with a Cu spacer layer in the structure CoFe/Cu(t)/Pt, which showed the largest damping is associated with the highest Pt PIM and the lowest damping with the loss of Pt PIM.…”

Section: Journal Of Applied Physicsmentioning

confidence: 92%

“…This proximity-induced moment (PIM) in the NM layer is typically confined to the interface with the FM. [68][69][70][71][72][73][74] In contrast, no PIM or a very small PIM has been measured in Pt layered with a range of oxide ferrimagnets. [75][76][77] The origin of PIM is associated with hybridization across the interface.…”

Section: Journal Of Applied Physicsmentioning

confidence: 99%

Interface enhanced precessional damping in spintronic multilayers: A perspective

Swindells

Atkinson

2022

Journal of Applied Physics

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In the past two decades, there have been huge developments in the understanding of damping in multilayered thin films and, more generally, in spin-transport in spintronic systems. In multilayered ferromagnetic (FM)/non-magnetic (NM) thin-film systems, observations of ferromagnetic resonant precession show a strong increase in the fundamental damping when the FM thin films are layered with heavy metals, such as Pt. These observations led to significant theoretical developments, dominated by the “spin-pumping” formalism, which describes the enhancement of damping in terms of the propagation or “pumping” of spin-current across the interface from the precessing magnetization into the heavy metal. This paper presents a perspective that introduces the key early experimental damping results in FM/NM systems and outlines the theoretical models developed to explain the enhanced damping observed in these systems. This is followed by a wider discussion of a range of experimental results in the context of the theoretical models, highlighting agreement between the theory and experiment, and more recent observations that have required further theoretical consideration, in particular, with respect to the role of the interfaces and proximity-induced magnetism in the heavy metal layer. The Perspective concludes with an outline discussion of spin-pumping in the broader context of spin-transport.

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“…The reduction of J c can be attributed to the improvement of spin transparency of Pt/Au/ Co interface leading to an increase in effective h sh of the system. In the Pt/Co interface, the spin current faces more dephasing 47 due to proximity-induced magnetization (PIM) in the Pt. 48,49 Introduction of the Au layer reduces the PIM in the Pt, 50 which leads to less dephasing of spin current, 51 and the spin transparency of Pt/Au/Co interface increases with respect to the Pt/Co interface.…”

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confidence: 99%

Interfacial engineering to manipulate the effective spin Hall angle of perpendicularly magnetized systems

Maji,

Chauhan,

Bhat

et al. 2024

Applied Physics Letters

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The spin current can be generated by passing an electric current through a heavy metal. The spin current generation depends on the spin Hall angle (θsh) of the material. To manipulate the effective θsh, a thin layer of Au has been introduced at the bottom Pt/Co and the top Co/Pt interfaces in Ta/Pt/Co/Pt based perpendicularly magnetic anisotropy systems, and current-induced magnetization reversal of Co has been studied to estimate Jc. The introduction of the Au layer at the top Co/Pt interface (Ta/Pt/Co/Au/Pt) did not produce any significant reduction in the Jc. However, a significant reduction of Jc (∼34%) has been observed, while the Au layer has been deposited at the bottom Pt/Co interface (Ta/Pt/Au/Co/Pt), indicating an enhancement in the value of θsh. We also performed a micromagnetic simulation to understand the qualitative change of the θsh. Micromagnetic simulation suggested that the θsh becomes 0.07 in Ta/Pt/Au/Co/Pt multilayer compared to θsh=0.05 of the Ta/Pt/Co/Pt system. Pt/Co/Au/Co/Au exhibits a reduction in Jc up to ∼30% and corresponds to θsh=0.09. A Ta capping layer has been introduced to inject more spin current into the Co layer since Pt and Ta have opposite spin Hall angles. The Jc lowers up to ∼58% in Ta/Pt/Au/Co/Pt/Ta multilayer, corresponding to θsh=0.23. We also achieved field-free switching at Jc=1.55×1011 by depositing an in-plane magnetized layer of Co in Ta/Pt/Au/Co/Pt/Ta/Co/Pt multilayer.

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Proximity-induced magnetism and the enhancement of damping in ferromagnetic/heavy metal systems

Cited by 11 publications

References 57 publications

Magnetic damping in ferromagnetic/heavy-metal systems: The role of interfaces and the relation to proximity-induced magnetism

Magnetic damping in ferromagnetic/heavy-metal systems: The role of interfaces and the relation to proximity-induced magnetism

Interface enhanced precessional damping in spintronic multilayers: A perspective

Interfacial engineering to manipulate the effective spin Hall angle of perpendicularly magnetized systems

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