Tuning of magnetic properties by alternating the order of hard/soft bilayers with various thicknesses
About: This article is published in Journal of Physics D.The article was published on 2019-05-23. It has received 9 citations till now. The article focuses on the topics: Magnetic anisotropy & Magnetic domain.
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TL;DR: In this article, the authors present a comprehensive study on the magnetization reversal in the Fe/NiFe bilayer system by alternating the order of the magnetic layers, showing that the magnetic parameters such as coercivity HC, and anisotropy field HK become almost doubled when a NiFe layer is grown over the Fe layers.
Abstract: We present a comprehensive study on the magnetization reversal in the Fe/NiFe bilayer system by alternating the order of the magnetic layers. All the samples show growth-induced uniaxial magnetic anisotropy due to the oblique angle deposition technique. Strong interfacial exchange coupling between the Fe and NiFe layers leads to single-phase hysteresis loops in the bilayer system. The strength of coupling being dependent on the interface changes upon alternating the order of magnetic layers. The magnetic parameters such as coercivity HC, and anisotropy field HK become almost doubled when a NiFe layer is grown over the Fe layers. This enhancement in the magnetic parameters is primarily dependent on the increase of the thickness and magnetic moment of the Fe–NiFe interfacial layer as revealed from the polarized neutron reflectivity (PNR) data of the bilayer samples. The difference in the thickness and magnetization of the Fe–NiFe interfacial layer indicates the modification of the microstructure by alternating the order of the magnetic layers of the bilayers. The interfacial magnetic moment increased by almost 18% when the NiFe layer was grown over the Fe layer. In spite of the different values of anisotropy fields and modified interfacial exchange coupling, the Gilbert damping constant values of the ferromagnetic bilayers remain similar to the single NiFe layer.
9 citations
TL;DR: In this article , the effect of transition metal dichalcogenides (TMD) on magnetic anisotropy in heterostructures of in-plane magnetization has been studied.
Abstract: Transition metal dichalcogenides (TMD) possess properties which makes them potential candidates for various spintronic applications. Heterostructures of TMD with magnetic thin film have been extensively considered for spin–orbital torque, enhancement of perpendicular magnetic anisotropy etc. However, the effect of TMD on magnetic anisotropy in heterostructures of in-plane magnetization has not been studied so far. Further the effect of the TMD on the domain structure and magnetization reversal of the ferromagnetic system is another important aspect to be understood. In this context we study the effect of MoS2, a well-studied TMD material, on magnetic properties of CoFeB in MoS2/CoFeB heterostructures. The reference CoFeB film possesses a weak in-plane anisotropy. However, when the CoFeB is deposited on MoS2 the in-plane anisotropy is enhanced as observed from magneto optic Kerr effect (MOKE) microscopy as well as ferromagnetic resonance (FMR). Magnetic domain structure and magnetization reversal have also been significantly modified for the MoS2/CoFeB bilayer as compared to the reference CoFeB layer. Frequency and angle dependent FMR measurement show that the magnetic anisotropy of CoFeB increases with increase in thickness of MoS2 in the MoS2/CoFeB heterostructures.
3 citations
TL;DR: In this article, the formation of spinterface at the interface of a bilayer thin film is investigated. And the authors show that the resulting spinterface can exhibit ferromagnetic properties in organic semiconductor/ferromagnetic bilayers.
Abstract: Organic semiconductor/ferromagnetic bilayer thin films can exhibit novel properties due to the formation of spinterface at the interface. Buckminsterfullerene (C60) has been shown to exhibit ferrom...
1 citations
TL;DR: In this paper , core-shell composite fibers with molar ratios of 1:1,1:2, 1:3,1.1:4 were prepared by coaxial electrostatic spinning and XRD revealed the coexistence of hexagonal ferrite and spinel phases in different proportions in the prepared composites.
1 citations
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TL;DR: In this article, the authors present a comprehensive study on the magnetization reversal in Fe/NiFe bilayer system by alternating the order of the magnetic layers, showing that the magnetic parameters such as coercivity HC, and anisotropy field HK become almost doubled when NiFe layer is grown over the Fe layers.
Abstract: We present a comprehensive study on the magnetization reversal in Fe/NiFe bilayer system by alternating the order of the magnetic layers. All the samples show growth-induced uniaxial magnetic anisotropy due to oblique angle deposition technique. Strong interfacial exchange coupling between the Fe and NiFe layers leads to the single-phase hysteresis loops in the bilayer system. The strength of coupling being dependent on the interface changes upon alternating the order of magnetic layers. The magnetic parameters such as coercivity HC, and anisotropy field HK become almost doubled when NiFe layer is grown over the Fe layers. This enhancement in the magnetic parameters is primarily dependent on the increase of the thickness and magnetic moment of Fe-NiFe interfacial layer as revealed from the polarized neutron reectivity (PNR) data of the bilayer samples. The difference in the thickness and magnetization of the Fe-NiFe interfacial layer indicates the modification of the microstructure by alternating the order of the magnetic layers of the bilayers. The interfacial magnetic moment increased by almost 18 % when NiFe layer is grown over the Fe layer. In spite of the different values of anisotropy fields and modified interfacial exchange coupling, the Gilbert damping constant values of the ferromagnetic bilayers remain similar to single NiFe layer.
1 citations
References
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TL;DR: In this article, the magnetic reversal process in epitaxial Sm-Co bilayer films has been studied and the authors present numerical solutions of a one-dimensional model that provides the spin configuration for each atomic layer.
Abstract: We present results on the magnetic reversal process in epitaxial Sm-Co(11\ifmmode\bar\else\textasciimacron\fi{}00)/TM (TM=Fe,Co) bilayer films prepared via magnetron sputtering. The magnetically hard Sm-Co films have 20-T uniaxial anisotropy and coercivities g3 T at room temperature, that double on cooling, as determined by magnetometry. The TM layers are exchange coupled to the Sm-Co layer and exhibit reversible demagnetization curves expected for an exchange-spring magnet. We also present numerical solutions of a one-dimensional model that provide the spin configuration for each atomic layer. Comparison of the experimental results with the model simulations indicates that our exchange-spring behavior can be understood from the intrinsic parameters of the hard and soft layers. The simulations are extended to realistically estimate the ultimate gain in the energy product that potentially can be realized based on the exchange hardening principle.
404 citations
TL;DR: In this paper, the magnetization dynamics of sputtered Co40Fe40B20 thin films in a wide range of thicknesses used as free layers in MgO-based magnetic tunnel junctions, with the technique of broadband ferromagnetic resonance (FMR).
Abstract: We have investigated the magnetization dynamics of sputtered Co40Fe40B20 thin films in a wide range of thicknesses used as free layers in MgO-based magnetic tunnel junctions, with the technique of broadband ferromagnetic resonance (FMR). We have observed a large interface-induced magnetic perpendicular anisotropy in the thin film limit. The out-of-plane angular dependence of the FMR measurement revealed the contributions of two different damping mechanisms in thick and thin film limits. In thinner films (<2 nm), two-magnon scattering and inhomogeneous broadening are significant for the FMR linewidth, while the Gilbert damping dominates the linewidth in thicker films (� 4n m). Lastly, we have observed an inverse scaling of Gilbert damping constant with film thickness, and an intrinsic damping constant of 0.004 in the CoFeB alloy film is determined. V C 2011 American Institute of Physics. [doi:10.1063/1.3615961]
216 citations
TL;DR: In this article, a first-order reversal curve sFORCd technique and vector magnetometry was used to investigate magnetization reversal in exchange-spring magnet films, and it was shown that the switching fields are clearly manifested by separate steps in both longitudinal and transverse hysteresis loops, as well as sharp boundaries in the FORC distribution.
Abstract: Magnetization reversal in exchange-spring magnet films has been investigated by a first-order reversal curve sFORCd technique and vector magnetometry. In Fe/epitaxial-SmCo films, the reversal proceeds by a reversible rotation of the Fe soft layer, followed by an irreversible switching of the SmCo hard layer. The switching fields are clearly manifested by separate steps in both longitudinal and transverse hysteresis loops, as well as sharp boundaries in the FORC distribution. In FeNi/ polycrystalline-FePt films, particularly with thin FeNi, the switching fields are masked by the smooth and step-free major loop. However, the FORC diagram still displays a distinct onset of irreversible switching and transverse hysteresis loops exhibit a pair of peaks, whose amplitude is larger than the maximum possible contribution from the FeNi layer alone. This suggests that the FeNi and FePt layers reverse in a continuous process via a vertical spiral. The successive versus continuous rotation of the soft/hard layer system is primarily due to the different crystal structure of the hard layer, which results in different anisotropies. © 2005 American Institute of Physics . fDOI: 10.1063/1.1954898g
143 citations
TL;DR: In this article, the collective picosecond magnetization dynamics in [Co/Pd]8 multilayers with perpendicular magnetic anisotropy was observed and the damping coefficient α was found to be inversely proportional to the Co layer thickness.
Abstract: We report the experimental observation of collective picosecond magnetization dynamics in [Co/Pd]8 multilayers with perpendicular magnetic anisotropy. The precession frequency shows large and systematic variation from about 5 GHz to about 90 GHz with the decrease in the Co layer thickness from 1.0 to 0.22 nm due to the linear increase in the perpendicular magnetic anisotropy. The damping coefficient α is found to be inversely proportional to the Co layer thickness and a linear relation between the perpendicular magnetic anisotropy and α is established. We discuss the possible reasons behind the enhanced damping as the d-d hybridization at the interface and spin pumping. These observations are significant for the applications of these materials in spintronics and magnonic crystals.
135 citations
TL;DR: In this article, structural and magnetic properties of epitaxial Sm-Co/Co superlattice films prepared via magnetron sputtering were investigated using X-ray diffraction and cross-sectional transmission electron microscopy.
Abstract: We present structural and magnetic properties of epitaxial Sm–Co/Co superlattice films prepared via magnetron sputtering. X-ray diffraction and cross-sectional transmission electron microscopy show that the films are structurally coherent. The oriented nature of the interleaved ferromagnetically “hard” and “soft” layers comprising the superlattice provides a realization of the ideal nanostructure of exchange-spring magnets as well as a model system to study layer thickness dependences of the magnetic properties. The superlattice films have an effective fourfold, in-plane magnetic anisotropy. Room-temperature hysteresis loops are relatively square and the demagnetization of the Co is reversible, as expected of exchange-spring magnets with aligned hard magnet layers.
114 citations