Femtosecond laser-induced spin dynamics in single-layer graphene/CoFeB thin films

Panda, Surya Narayan; Majumder, Sudip; Choudhury, Samiran; Bhattacharya, A.A.; Sinha, Subhajit; Barman, Anjan

doi:10.1039/d1nr03397b

Cited by 9 publications

(20 citation statements)

References 71 publications

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“…Also, no evidence of any significant anisotropy is found in this 10 nm-thick amorphous CoGd film in contrast to thinner ferromagnetic films. 25 The effective damping (α eff ) of this film is calculated by using the following formula: 45 α eff contains all the contributions from intrinsic and extrinsic damping in the system. The values α eff (≥0.03) for the CoGd film within our experimental field regime are close to the reported value (∼0.10) in the literature.…”

Section: Resultsmentioning

confidence: 99%

“…Significantly, the spin-pumping effect, which does not necessarily require any charge current, is demonstrated for monolayer graphene and graphite. 19,24,25 An inverse relationship between damping and demagnetization time is established in the graphene/CoFeB interface from time-resolved magneto-optical Kerr effect (TRMOKE) microscopy measurements. 25 The modulation in the Gilbert damping shows dependence on the spin-mixing conductance and spin transparency of the interface in the presence of graphene similar to other conventional heavy metals.…”

mentioning

confidence: 99%

“…19,24,25 An inverse relationship between damping and demagnetization time is established in the graphene/CoFeB interface from time-resolved magneto-optical Kerr effect (TRMOKE) microscopy measurements. 25 The modulation in the Gilbert damping shows dependence on the spin-mixing conductance and spin transparency of the interface in the presence of graphene similar to other conventional heavy metals. 26 The dynamics of Permalloy adjacent to graphene grown by the chemical vapor deposition method was also studied using ferromagnetic resonance techniques.…”

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confidence: 99%

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Accelerated Ultrafast Magnetization Dynamics at Graphene/CoGd Interfaces

et al. 2022

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Atomically thin graphene layers can act as a spin-sink material when adjacent to a nanoscale magnetic surface. The enhancement in the extrinsic spin−orbit coupling (SOC) strength of graphene plays an important role in absorbing the spin angular momentum injected from the magnetic surface after perturbation with an external stimulus. As a result, the dynamics of the excited spin system is modified within the magnetic layer. In this paper, we demonstrate the modulation of ultrafast magnetization dynamics at graphene/ferrimagnet interfaces using the time-resolved magneto-optical Kerr effect (TRMOKE) technique. Magnetically modified interfaces with a systematic increase in the number of graphene layers coupled with the 10 nm-thick Co 74 Gd 26 layer are studied. We find that the variation in the dynamical parameters, i.e., ultrafast demagnetization time, remagnetization times, decay time, effective damping, precessional frequency, etc., observed at different time scales is interconnected. The demagnetization time and decay time for the ferrimagnet become approximately two times faster than the corresponding intrinsic values. We found a possible correlation between the demagnetization time and damping. The effect is more pronounced for the interfaces with monolayer graphene and graphite. The spin-mixing conductance is found to be approximately 0.8 × 10 15 cm −2 . The effect of SOC, pure spin current, the appearance of structural defects, and thermal properties at the graphene/ferrimagnet interface are responsible for the modifications of several dynamical parameters. This work demonstrates some important properties of the graphene/ferrimagnet interface which may unravel the possibilities of designing spintronic devices with elevated performance in the future.

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Section: Resultsmentioning

confidence: 99%

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confidence: 99%

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confidence: 99%

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Accelerated Ultrafast Magnetization Dynamics at Graphene/CoGd Interfaces

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“…[28] This was later argued and exper-imentally demonstrated in different systems. [17,18,29] The femtosecond laser-induced spin current is very short-lived (subpicosecond), while spin-pumping-induced spin current can live for nanoseconds. However, despite occurring in different timescales, their physical natures are similar.…”

Section: Introductionmentioning

confidence: 99%

“…[30] They have established an inverse relationship between fast remagnetization time (𝜏 r ) and 𝛼 due to the dominant contribution of magnon dynamics to the remagnetization process. Despite some efforts, [16][17][18]25,29,31,32] a systematic study on various effects of SOC of NM materials on the ultrafast demagnetization and fast remagnetization in NM/FM heterostructures has not been performed so far. In particular, the relationship among the 𝜏 m , 𝜏 r , and 𝛼 with the SOC strength of NM in NM/FM heterostructures has never been experimentally demonstrated or theoretically formulated.…”

Section: Introductionmentioning

confidence: 99%

Role of Spin–Orbit Coupling on Ultrafast Spin Dynamics in Nonmagnet/Ferromagnet Heterostructures

et al. 2022

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Spin-orbit coupling (SOC), the interaction between spin and orbital angular momentum of electrons, is imperative to control magnetic properties of nonmagnet (NM)/ferromagnet (FM) heterostructures and design energy-efficient and faster spin-based devices. Here, femtosecond pulsed laser-induced time-resolved magneto-optical Kerr effect magnetometry is employed to investigate magnetization dynamics in different NM/Co 20 Fe 60 B 20 heterostructures, where the NM layer varies as Cu, Ta, W, Pt, Ta/Ru/Ta, and Si/SiO 2 (no underlayer) that differ in SOC strength. It is observed that there is a systematic variation in ultrafast demagnetization time (𝝉 m ), fast remagnetization time (𝝉 r ), and Gilbert damping parameter (𝜶) with the SOC strength of the underlayer and an inverse relationship between 𝜶 and 𝝉 m , 𝝉 r is established due to the dominant contribution of spin current transport in ultrafast demagnetization and fast remagnetization processes. The spin pumping formalism estimates the effective spin-mixing conductance (G eff ) for different interfaces, which signifies that the high SOC strength of underlayers results in high G eff indicating more efficient transport of spin current through it. This study suggests that the SOC strength of the NM underlayer plays a significant role in controlling the ultrafast demagnetization process through interfacial spin current transport in a NM/FM heterostructure which can be beneficial for the development of ultrafast spintronics devices.

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Ferromagnetic Elements in Two‐Dimensional Materials: 2D Magnets and Beyond

Papavasileiou,

Menelaou,

Sarkar

et al. 2023

Adv Funct Materials

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Ferromagnetism in 2D materials has attracted tremendous interest from the scientific community thanks to its potential for the design of magnetic materials with unique properties. The presence of a ferromagnetic element in a 2D material can improve the existing properties and offer new ones, giving rise to the development of manifold applications. This review focuses on recent advances and perspectives of 2D materials that bear at least one ferromagnetic element (iron, cobalt, nickel) as i) structural constituent, ii) dopant atom, or iii) adjacent atom through proximity effect. By describing in detail the magnetic properties that have emerged so far, their potential to form next‐generation 2D magnets is discussed. Moreover, the contribution of such 2D materials is analyzed in various applications (electrochemical, photochemical, optical, and electronic), aiming to explore further functionalities and capabilities of ferromagnetic elements, apart from their magnetic nature. Special attention is given to gadolinium and other rare earth elements that display a ferromagnetic order even at ultra‐low temperatures and form part of 2D structured materials, with particularly appealing properties deriving from their 4f electrons.

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Femtosecond laser-induced spin dynamics in single-layer graphene/CoFeB thin films

Abstract: Graphene/Ferromagnet hybrid heterostructure is an important building block of spintronics due to unique ability of graphene to transport spin current over unprecedented distance and possible increase in its spin-orbit coupling...

Cited by 9 publications

References 71 publications

Accelerated Ultrafast Magnetization Dynamics at Graphene/CoGd Interfaces

Accelerated Ultrafast Magnetization Dynamics at Graphene/CoGd Interfaces

Role of Spin–Orbit Coupling on Ultrafast Spin Dynamics in Nonmagnet/Ferromagnet Heterostructures

Ferromagnetic Elements in Two‐Dimensional Materials: 2D Magnets and Beyond

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