Magnetic properties and magnetization reversal process of L10 FePt/Fe bilayers magnetic thin films

Liu, Liwang; Sheng, Wen; Bai, Junfeng; Cao, Jiangwei; Lou, Yuanfu; Wang, Ying; Wei, Fulin; Lu, Jia Grace

doi:10.1016/j.apsusc.2012.05.006

Cited by 15 publications

(6 citation statements)

References 21 publications

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“…As the temperature increases, there is a transition from this two-step process to a single step due a decrease in the FePt anisotropy relative to the interface exchange. This reduction in the coercivity agrees well with experimental measurements, which observed that the coercivity is reduced to approximately half with an equal thickness of Fe on top of L1 0 FePt [21]. At each temperature, the coercive field has been extracted, which is shown in Fig.…”

Section: Magnetization Reversal At Finite Temperaturesupporting

confidence: 88%

Anomalous damping dependence of the switching time in Fe/FePt bilayer recording media

et al. 2019

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Gilbert damping plays a significant role in magnetic reversal processes, and it determines the timescale of the switching. Here we investigate the properties of exchange-coupled composite media and the dependence of the switching time on the damping constant of the soft layer using atomistic spin dynamics. For a bilayer Fe/FePt medium, we find an anomalous increase of the switching time with increasing soft layer damping constant. The reversal occurs via a high-temperature exchange spring, and we show that the increase in the switching time is related to a corresponding increase in the time to establish the exchange spring. This phenomenon is delicately balanced in that the switching time increase occurs only in fields close to the coercivity.

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Section: Magnetization Reversal At Finite Temperaturesupporting

confidence: 88%

Anomalous damping dependence of the switching time in Fe/FePt bilayer recording media

et al. 2019

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“…As a soft magnetic layer, Fe is a commonly employed material, because of its small magnetocrystalline anisotropy and large saturation magnetization. [54][55][56][57][58][59][60][61] Different bilayer stacks as well as more complex ECC structures like trilayers 62 were proposed, and their magnetic properties dependent on the soft layer thickness were investigated, [63][64][65] demonstrating the superior performance of ECC media.…”

mentioning

confidence: 99%

Review Article: FePt heat assisted magnetic recording media

Weller¹,

Parker²,

Mosendz³

et al. 2016

Journal of Vacuum Science &Amp; Technology B, Nanotechnology and Microelectronics: Materials, Processing, Measurement, and Phen

151

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Heat-assisted magnetic recording (HAMR) media status, requirements, and challenges to extend the areal density (AD) of magnetic hard disk drives beyond current records of around 1.4 Tb/in.2 are updated. The structural properties of granular high anisotropy chemically ordered L10 FePtX-Y HAMR media by now are similar to perpendicular CoCrPt-based magnetic recording media. Reasonable average grain diameter ⟨D⟩ = 8–10 nm and distributions σD/D ∼ 18% are possible despite elevated growth temperatures TG = 650–670 °C. A 2× reduction of ⟨D⟩ down to 4–5 nm and lowering σD/D < 10%–15% are ongoing efforts to increase AD to ∼4 Tb/in.2. X = Cu ∼ 10 at. % reduces the Curie temperature TC by ∼100 K below TC,bulk = 750 K, thereby lowering the write head heat energy requirement. Multiple FePtX-Y granular layers with Y = 30–35 vol. % grain-to-grain segregants like carbides, oxides, and/or nitrides are used to fully exchange decouple the grains and achieve cylindrical shape. FePt is typically grown on fcc MgO (100) seedlayers to form well oriented FePt (002). A FePt lattice parameter ratio c/a ∼0.96 and high chemical order S > 0.90 result in magnetic anisotropy KU ∼ 4.5 × 107 erg/cm3, and only 25% below the FePt single crystal value KU = 6.6 × 107 erg/cm3 has been achieved in 7–8 nm diameter grains. Switching field distributions depend on anisotropy field (HK) distributions, which are currently of the order of ΔHK/HK ∼ 10% (ΔHK ∼ 10–12 kOe, HK ∼ 10–11 T) at room temperature. High thermal conductivity heat sink layers, including Ag, Au, Cu, and Cr, are used to optimize the cooling rate and maximize the down- and cross-track thermal gradient, which determines the achievable track density.

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“…Magnetoresistance was measured by passing a DC current while sweeping the magnetic field and imaging the domains simultaneously. the domains vanish, indicating a lack of PMA, which is associated with a decrease in anisotropy energy Ku with ion implantation [30][31][32]. These results indicate that the B+ implantation is able to modify the magnetic properties of Co/Pd multilayer and that the implantation depth can be controlled by changing the Ta overcoat thickness [33][34][35][36].…”

Section: Methodsmentioning

confidence: 99%

Synaptic element for neuromorphic computing using a magnetic domain wall device with synthetic pinning sites

Jin¹,

Gan²,

Tan³

et al. 2019

J. Phys. D: Appl. Phys.

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The ability to make devices that mimic the human brain has been a subject of great interest in scientific research in recent years. Current artificial intelligence algorithms are primarily executed on the von Neumann hardware. This causes a bottleneck in processing speeds and is not energy efficient. In this work, we have demonstrated a synaptic element based on a magnetic domain wall device. The domain wall motion was controlled with the use of synthetic pinning sites, which were introduced by Boron (B+) ion-implantation for local modification of the magnetic properties. The magnetization switching process of a Co/Pd multilayer structure with perpendicular magnetic anisotropy was observed by using MagVision Kerr microscopy system. The B+ implantation depth was controlled by varying the thickness of a Ta overcoat layer. The Kerr microscopy results correlate with the electrical measurements of the wire which show multiple resistive states. The control of the domain wall motion with the synthetic pinning sites is demonstrated to be a reliable technique for neuromorphic applications.

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Magnetic properties and magnetization reversal process of L10 FePt/Fe bilayers magnetic thin films

Cited by 15 publications

References 21 publications

Anomalous damping dependence of the switching time in Fe/FePt bilayer recording media

Anomalous damping dependence of the switching time in Fe/FePt bilayer recording media

Review Article: FePt heat assisted magnetic recording media

Synaptic element for neuromorphic computing using a magnetic domain wall device with synthetic pinning sites

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