Enhancement of zero-field skyrmion density in [Pt/Co/Fe/Ir]2 multilayers at room temperature by the first-order reversal curve

Ma, Mangyuan; Ang, Calvin Ching Ian; Li, Yong; Pan, Zizhao; Gan, Wei Liang; Lew, Wen Siang; Ma, Fusheng

doi:10.1063/5.0004432

Cited by 13 publications

(9 citation statements)

References 41 publications

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“…While previous works had identified the fracturing and annihilation process during the negative field sweep [35][36][37][38][47][48][49], the lack of analysis of the process associated with the positive field sweep can lead to incomplete descriptions of the peaks. One main contradiction is the process of stripe fracturing into multiple shorter segments or skyrmions that continues to occur even when the upper peak had been almost completely translated off the FORC diagram.…”

Section: Skyrmion Transformations At Forc Featuresmentioning

confidence: 99%

“…FORC is especially suitable for the characterization of magnetic skyrmions as it reveals magnetic states and transitions that are imperceivable in a major hysteresis loop or even by optical imaging techniques [35]. The application of the FORC technique was demonstrated to be useful in maximizing zerofield skyrmions based on the projected FORC distribution peaks onto the reversal fields [36,37]. A recent work extended its use to determine a pure Néel skyrmion structure from the disappearance of the FORC distribution trough [38].…”

Section: Introductionmentioning

confidence: 99%

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Temperature-modulated magnetic skyrmion phases and transformations analysis from first-order reversal curve study

et al. 2021

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We performed a temperature-modulated first-order reversal curve (FORC) study on a Pt/Co/Fe/Ir magnetic stack that exhibited a magnetic phase transition from isolated skyrmions to skyrmion lattice with increasing temperature. Using in situ magneto-optical Kerr imaging, a generalized description of domain transformations associated with the FORC distribution peaks at both their reversal and sweeping field are derived to allow for direct analysis from the FORC diagram. The sweeping field of the peak, which is commonly ignored in analysis, is identified as the process of domain propagation or nucleation towards terminal domain separation. This process is found to be essential in inducing magnetization irreversibility to reveal domain transformations. In addition, a model characterized by the FORC distribution peaks was developed to describe the transition from the isolated skyrmion to skyrmion lattice phase as well as to identify important field ranges for the transformations. This study establishes an intuitive form of analysis for the otherwise abstract data of FORC distribution for the characterization of magnetic skyrmions in the active field of skyrmionics.

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Section: Skyrmion Transformations At Forc Featuresmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Temperature-modulated magnetic skyrmion phases and transformations analysis from first-order reversal curve study

et al. 2021

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“…In asymmetric ferromagnetic multilayer system, the DMI is induced by the high interfacial spin orbit coupling resulting from symmetric breaking. Since DMI and anisotropy are material property and geometry dependent, so, in order to stabilize these skyrmions and define a particular chirality, combination of different HM/FM structures are being investigated [4]. The other important parameters and effects that define the size and density of skyrmions include Zeeman field and the exchange coefficient.…”

Section: Introductionmentioning

confidence: 99%

Creation and Annihilation of Magnetic Skyrmions for Neuromorphic Computing Applications

Lone¹,

Ganguly²,

Divyanshu³

et al. 2021

Preprint

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In this work we present the creation, annihilation and dynamics of a topologically protected magnetic structure, a skyrmion, for neuromorphic computing application. We study the effect of Dzyaloshinskii Moriya interaction (DMI) and surface anisotropy on the skyrmion density. The relation between skyrmion annihilation threshold anisotropy Kth and DMI coefficient is evaluated. Furthermore, the skyrmion diameter dependence on these two parameters is studied. Using MOKE analysis we study the effect of external magnetic field on the skyrmion density and predict the threshold magnetic field for the transition of magnetic texture from Labriynth domains to skyrmions. These results are further supported by the MuMax simulations. The spin orbit torque SOT manipulation of skyrmion size and density is also presented for skyrmion applications in the race-track memory and neuromorphic computing. Motivated by the results, we propose a Skyrmionic neuromorphic device and using SOT switching mechanism, show its applicability as spintronic synapse and neuron. The MuMax simulations are coupled to the Non- Equilibrium Green’s Function formalism to model the neuron and synapse behavior. Finally, we conclude with the possibility of using these devices for pattern recognition and other unconventional computing paradigms.

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“…The ability to identify these subtle processes has been demonstrated by the First Order Reversal Curve (FORC) technique, which provides a magnetic fingerprint of the interactions and reversal processes occuring in magnetic materials [15,16]. Recent studies have begun utilizing FORC in skyrmion-hosting multilayers to study field history control of zero-field skyrmion population [17,18], while simultaneously revealing magnetic reversal mechanisms influenced by the skyrmion configuration [17]. Indeed, the variety of magnetic interactions and skyrmion configurations realizable in different thin film heterostructures offer a rich resource for FORC studies.…”

Section: Introductionmentioning

confidence: 99%

Magnetization reversal signatures of hybrid and pure Néel skyrmions in thin film multilayers

et al. 2020

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We report a study of the magnetization reversals and skyrmion configurations in two systems -Pt/Co/MgO and Ir/Fe/Co/Pt multilayers, where magnetic skyrmions are stabilized by a combination of dipolar and Dzyaloshinskii-Moriya interactions (DMI). First Order Reversal Curve (FORC) diagrams of low-DMI Pt/Co/MgO and high-DMI Ir/Fe/Co/Pt exhibit stark differences, which are identified by micromagnetic simulations to be indicative of hybrid and pure Néel skyrmions, respectively. Tracking the evolution of FORC features in multilayers with dipolar interactions and DMI, we find that the negative FORC valley, typically accompanying the positive FORC peak near saturation, disappears under both reduced dipolar interactions and enhanced DMI. As these conditions favor the formation of pure Neel skyrmions, we propose that the resultant FORC feature -a single positive FORC peak near saturation -can act as a fingerprint for pure Néel skyrmions in multilayers. Our study thus expands on the utility of FORC analysis as a tool for characterizing spin topology in multilayer thin films.

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Enhancement of zero-field skyrmion density in [Pt/Co/Fe/Ir]2 multilayers at room temperature by the first-order reversal curve

Cited by 13 publications

References 41 publications

Temperature-modulated magnetic skyrmion phases and transformations analysis from first-order reversal curve study

Temperature-modulated magnetic skyrmion phases and transformations analysis from first-order reversal curve study

Creation and Annihilation of Magnetic Skyrmions for Neuromorphic Computing Applications

Magnetization reversal signatures of hybrid and pure Néel skyrmions in thin film multilayers

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