Phase diagram in exchange-coupled CoTb/[Co/Pt] multilayer-based magnetic tunnel junctions

A single femto-second optical pulse can fully reverse the magnetization of a film within picoseconds. Such fast operation hugely increases the range of application of magnetic devices. However, so far, this type of ultrafast switching has been restricted to ferri-magnetic GdFeCo films. In contrast, all optical switching of ferro-magnetic films require multiple pulses, thereby being slower and less energy efficient. Here, we demonstrate magnetization switching induced by a single laser pulse in various ferromagnetic Co/Pt multilayers grown on GdFeCo, by exploiting the exchange coupling between the two magnetic films. Table-top picoseconds. This coupling approach will allow ultrafast control of a variety of magnetic films, critical for applications.

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“…[13][14][15] . An RKKYtype of exchange [13][14][15][16] or a dipolar orange peel coupling 13,17 could explain such AFM coupling.…”

Section: Main Textmentioning

confidence: 99%

“…We thus attribute the net coupling to an RKKY-type of exchange as reported in Refs. [13][14][15][16] .…”

Section: Main Textmentioning

confidence: 99%

Single shot ultrafast all optical magnetization switching of ferromagnetic Co/Pt multilayers

Gorchon

Lambert

Yang

et al. 2017

Applied Physics Letters

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“…Furthermore, exchange-coupled systems employing ferrimagnetic (FI) heavy rare earth (RE)-3d transition metal (TM) alloys provide high tunability, interfacial exchange interaction, and zero magnetic moment at the compensation temperature T comp , 5 − 17 which is highly beneficial for many applications such as spin valves 18 − 23 and magnetic tunnel junction devices. 24 Below T comp , the magnetic moment of the RE atoms dominates, which leads to an antiparallel alignment of the net magnetic moments of the FI layer when coupled to a ferromagnetic (FM) layer. As a consequence, a positive horizontal shift of the hysteresis loop of the magnetically softer layer is typically observed after saturation in the positive field direction.…”

Section: Introductionmentioning

confidence: 99%

Microscopic Origin of Magnetization Reversal in Nanoscale Exchange-Coupled Ferri/Ferromagnetic Bilayers: Implications for High Energy Density Permanent Magnets and Spintronic Devices

Heigl

Vogler

Mandru

et al. 2020

ACS Appl. Nano Mater.

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Giant exchange bias shifts of several Tesla have been reported in ferrimagnetic/ferromagnetic bilayer systems, which could be highly beneficial for contemporary high energy density permanent magnets and spintronic devices. However, the lack of microscopic studies of the reversal owing to the difficulty of measuring few nanometer-wide magnetic structures in high fields precludes the assessment of the lateral size of the inhomogeneity in relation to the intended application. In this study, the magnetic reversal process of nanoscale exchange-coupled bilayer systems, consisting of a ferrimagnetic TbFeCo alloy layer and a ferromagnetic [Co/Ni/Pt] N multilayer, was investigated. In particular, minor loop measurements, probing solely on the reversal characteristics of the softer ferromagnetic layer, reveal two distinct reversal mechanisms, which depend critically on the thickness of the ferromagnetic layer. For thick layers, irreversible switching of the macroscopic minor loop is observed. The underlying microscopic origin of this reversal process was studied in detail by high-resolution magnetic force microscopy, showing that the reversal is triggered by in-plane domain walls propagating through the ferromagnetic layer. In contrast, thin ferromagnetic layers show a hysteresis-free reversal, which is nucleation-dominated due to grain-to-grain variations in magnetic anisotropy of the Co/Ni/Pt multilayer and an inhomogeneous exchange coupling with the magnetically hard TbFeCo layer, as confirmed by micromagnetic simulations.

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“…Additional possibilities are opened with the use of magnetic films with perpendicular (easy-axis) anisotropy. The fabrication of nanostructures based on multilayer systems consisting of films with easy-axis and easy-plane anisotropy enables the realization of structures with essentially noncollinear magnetization distribution [ 8 , 9 , 10 ] for magnetic devices with vertical architectures. Additionally, in recent years, new approaches to modifying the properties of magnetic films by focused ion beams have been developed [ 11 , 12 , 13 , 14 , 15 ].…”

Section: Introductionmentioning

confidence: 99%

Magnetic Force Microscopy of Nanostructured Co/Pt Multilayer Films with Perpendicular Magnetization

et al. 2017

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Abstract:We present the results of magnetic force microscopy investigations of domain structures in multilayer [Co (0.5 nm)/Pt (1 nm)] 5 thin film structures (denoted hereafter as Co/Pt) modified by additional Co capping layers and by ion irradiation. It is demonstrated that a Co capping layer essentially changes the domain structure and decreases the threshold of magnetization reversal, due to the formation of noncollinear magnetization in Co/Pt. It is shown that local irradiation with a focused He + ion beam enables the formation of regions with decreased easy-axis anisotropy (magnetic bubbles) that have the inverse magnetization direction in the demagnetized state of Co/Pt. The experimental results demonstrate that the magnetic bubbles can be switched using a probe of a magnetic force microscope. The possible application of these effects for the development of magnetic logic and data storage systems is discussed.

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Phase diagram in exchange-coupled CoTb/[Co/Pt] multilayer-based magnetic tunnel junctions

Cited by 14 publications

References 26 publications

Single shot ultrafast all optical magnetization switching of ferromagnetic Co/Pt multilayers

Single shot ultrafast all optical magnetization switching of ferromagnetic Co/Pt multilayers

Microscopic Origin of Magnetization Reversal in Nanoscale Exchange-Coupled Ferri/Ferromagnetic Bilayers: Implications for High Energy Density Permanent Magnets and Spintronic Devices

Magnetic Force Microscopy of Nanostructured Co/Pt Multilayer Films with Perpendicular Magnetization

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