A5055668762- Magnetic properties of thin films
- Theoretical and Computational Physics
- Adhesion, Friction, and Surface Interactions
- Magnetic Properties and Applications
- Characterization and Applications of Magnetic Nanoparticles
- Physics of Superconductivity and Magnetism
- Advanced Data Storage Technologies
- Metallic Glasses and Amorphous Alloys
- Near-Field Optical Microscopy
- Geomagnetism and Paleomagnetism Studies
- Phase-change materials and chalcogenides
- Magneto-Optical Properties and Applications
- Workplace Violence and Bullying
- Photonic Crystals and Applications
- Marine animal studies overview
- Underwater Acoustics Research
- Electromagnetic Simulation and Numerical Methods
- Cellular Automata and Applications
- Oceanographic and Atmospheric Processes
- Parallel Computing and Optimization Techniques
First Institute of Oceanography
2025
Ministry of Natural Resources
2025
Qingdao National Laboratory for Marine Science and Technology
2025
Seagate (United States)
2015-2024
Tri-Service General Hospital
2018
University of Minnesota
2012-2015
Heat-assisted magnetic recording (HAMR) is being developed as the next generation technology. Critical components of this technology, such plasmonic near-field transducer (NFT) and high anisotropy granular FePt media, well performance reliability fully integrated drives have been reported. This paper will focus on progress challenges HAMR including microstructure thermal design testing characterization at field temperature. Due to importance Curie temperature distribution, σT <sub...
A new scheme for the simulation of heat-assisted magnetic recording (HAMR) that systematically includes fluctuating material properties above a predefined length scale, while retaining magnetostatic interactions, is introduced. Renormalized media parameters <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">M</i> <sub xmlns:xlink="http://www.w3.org/1999/xlink">s</sub> , xmlns:xlink="http://www.w3.org/1999/xlink">K</i>...
Multi-level magnetic recording is a new concept for increasing the data storage capacity of hard disk drives. However, its implementation has been limited by lack suitable media capable storing information at multiple levels. Herein, we overcome this problem developing dual FePt-C nanogranular films separated Ru-C breaking layer with cubic crystal structure. The FePt grains in bottom and top layers developed exhibited different effective magnetocrystalline anisotropies Curie temperatures....
Abstract The generic problem of extracting information on intrinsic particle properties from the whole class interacting magnetic fine systems is a long standing and difficult inverse problem. As an example, Switching Field Distribution (SFD) important quantity in characterization systems, its determination many technological applications, such as recording media, especially challenging. Techniques first order reversal curve (FORC) methods, were developed to extract SFD macroscopic...
Marine acoustic field prediction (MAFP) is essential for a variety of application scenarios. Given the rapid temporal changes in ocean environment, MAFP requires time-dependent parameters. Ocean models are generally employed to provide dynamic parameters water column; however, few extend this capability sediments. Nonetheless, both observations and simulations have revealed that sediment temperature variations shallow seas significantly affect properties. This paper proposes conducting using...
Ensemble waveform analysis is used to calculate signal noise ratio (SNR) and other recording characteristics from micromagnetically modeled heat assisted magnetic waveforms measured at both drive spin-stand level. Using windowing functions provides the breakdown between transition remanence SNRs. In addition, channel bit density (CBD) can be extracted ensemble using di-bit extraction method. Trends in SNR, CBD as a function of ambient temperature constant track width showed good agreement...
Transition jitter is one of the most important parameters for evaluating potential areal density Heat Assisted Magnetic Recording. However, obtaining this either experimentally or through micro-magnetic simulation time consuming. Here, we show that more easily calculated thermal switching probability distribution (SPD) can serve as a substitute. In particular, provide an equation relating standard deviation write temperature to jitter. The verified three critical noise sources: Tc variance,...
Heat-assisted magnetic recording (HAMR) is being developed as the next generation technology. Critical components of this technology, such plasmonic near-field transducer and high anisotropy granular FePt media, well demonstrations fully integrated drives have been reported. One remaining ongoing challenges in general HAMR particular has demonstration linear density recording, approaching grain-size (GS) limit a clear pathway to smaller GSs while maintaining good properties distributions....
Composite FeRh/FePt for heat-assisted magnetic recording media is investigated with micromagnetic simulation. It found to potentially lower temperature, while retaining high anisotropy field gradient. The transition width predicted depend on the cooling rate. thickness of FeRh layer and applied can significantly affect switching time FePt layer, therefore alter performance. Applied magnitudes angles are identified that allow successful within 100 ps. shown using up 15 nm 6 FePt, jitter 5.6...
The auto-correlation signal-to-noise (ACSN) method is employed on micromagnetically modeled heat-assisted magnetic recording (HAMR) readback waveforms and compared with experimental ACSN data. breakdown between transition ratio (SNR) remanence SNR provided for both measured Good agreement observed simulated SNRs as a function of laser power linear density. An efficiency factor that relates maximum temperature in the media to applied current obtained by combining Usage this methodology...
Curvature of recorded bit and skew are two factors limiting further improvement the areal density capacity heat-assisted magnetic recording. Performance degradation due to curvature is evaluated using micromagnetic modeling spin-stand measurements. Here, we propose techniques for reduction. One a forked writer which can provide cross-track field gradient that, combined with thermal profile, mitigates transitions. The other near-field transducer (NFT) design flat temperature contour at write...
Feasibility of heat assisted magnetic recording for granular and bit-patterned media (BPM) is evaluated in the context various noises. Using micromagnetic simulation renormalized cells, we predict that jitter only 0.58 nm at a head speed 10 m/s bilayer structure FeRh/FePt when grain size 3.2 nm, validating possibility 6 Tb/in <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> . We propose new FePt/Cr/X/FePt uses Cr layer to produce an...
A simple torque-based method for calculating the transient behavior of temperature-dependent magnetic anisotropy is introduced. Using this we obtain several physical quantities at finite temperature, including effective anisotropy, field, and their fluctuations, that are crucial to heat-assisted recording (HAMR). We show use a composite grain includes high Curie temperature soft layer reduces fluctuations.
Recording simulations on heat-assisted magnetic recording (HAMR) are implemented to study the dependences of grain size and Gilbert damping performance. Modified temperature shift for renormalized media cells needed address non-equilibrium nature HAMR process. It is found that using smaller grains helps reduce transition jitter but increases track width. Larger also effective in reducing jitter. Finally, applicability this simulation method corroborated by comparing with experimental results.
How far can we miniaturize magnetic recording media? Reducing grain size and layer thickness nearly to the atomic level requires finer handling than in typical micromagnetic calculations. The authors develop atomistic simulation of spin dynamics study magnetization reversal complex granular media, optimize performance push areal density above 1 Tbit/in${}^{2}$. They demonstrate importance magnetostatic interactions inter- intralayer exchange couplings, visualize switching at reveal...
Heat-assisted magnetic recording (HAMR) can support extremely high areal densities based on the thermal stability argument. However, significant challenges remain to reduce switching probability distribution (SPD) improve media SNR. Exchange coupled composite (ECC)-type architectures, such as designs employed in perpendicular media, are being explored for HAMR and show potential promise at reducing SPD. In this article, we propose a new approach design that consisting of an exchange...
A micro-magnetic simulation model to evaluate microwave-assisted magnetic recording (MAMR) has been developed. Optimization of the spin torque oscillator with ac field strength, head geometry, and oscillating frequency is reported. Realistic conditions, including media properties parameters, are implemented show benefits challenges MAMR. We found out-of-plane component causes erasure when medium anisotropy low for system during writing process even while ferromagnetic resonance helping...
The heat-assisted magnetic recording performance at varying data rate conditions is investigated using an ensemble waveform analysis method. This method decouples the transition signal-to-noise ratio (SNR) and remanence SNR from total spatial media SNR. For rates below 2200 Mbpsi, noises are largely independent of writer field rise time (RT) values less than 150 ps. Above a significantly degraded for slowest RTs considered. all values, sees minimal degradation with increasing RT. At highest...
Downtrack thermal gradient (DTG) is calculated for heat-assisted magnetic recording (HAMR) systems in both spin-stand experiment and micromagnetic model. DTG an important parameter HAMR. It describes the change temperature vicinity of write position. Recording conditions media properties affect switching process, which turn affects measured DTG. Trends versus different such as linear velocity applied field showed very good agreement between The model also used to quantify effect on from...
Magnetic hard disk drives (HDDs) store over 90% of the world's digital data enabling internet and economical access to power everything from social media self-driving cars. Heat assisted magnetic recording (HAMR) is being developed as next system for HDDs. HAMR will bring profound changes HDD components architecture, incorporating laser diodes in an innovative plasmonic light delivery into heads, novel nano-magnetic materials layer architectures [1]. Seagate demonstrated promise with a 1 -2...
Heat-Assisted Magnetic Recording (HAMR) is expected to be the next-generation magnetic recording technology: it designed meet increasing higher areal density demands from cloud storage. Until now, there are no feasible solutions address nm-scale Curie temperature variance in FePt-based single layer media. This leading noise source, and thus limits further development of HAMR technology. Here, we describe a superparamagnetic write process that can greatly mitigate impact by information at...
The generic problem of extracting information on intrinsic particle properties from the whole class interacting magnetic fine systems is a long standing and difficult inverse problem. As an example, Switching Field Distribution (SFD) important quantity in characterization systems, its determination many technological applications, such as recording media, especially challenging. Techniques first order reversal curve (FORC) methods, were developed to extract SFD macroscopic measurements....
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Areal density increases in conventional perpendicular magnetic recording are becoming increasingly difficult to achieve. Heat assisted is viewed as a potential technique extend into the multiple-terabit range. Over last 5 years, we have performed extensive simulations of Assisted Magnetic Recording on both granular and bit-patterned media. For this purpose, represent behavior media near Curie temperature with renormalized blocks spins order 1 nm <sup...