A practical detector for 2-D magnetic storage

2005 ◽  
Author(s):  
M. Power
Keyword(s):  
Magnetic Storage

Magnetization dynamics of irradiation-fabricated perpendicularly magnetized dots inside a softer magnetic matrix

2003 ◽  
Vol 777 ◽  
Author(s):  
T. Devolder ◽  
M. Belmeguenai ◽  
C. Chappert ◽  
H. Bernas ◽  
Y. Suzuki
Keyword(s):  
Domain Wall ◽  
Magnetic Anisotropy ◽  
Magnetization Reversal ◽  
Ion Irradiation ◽  
Magnetic Nanostructures ◽  
Magnetic Storage ◽  
Exchange Field ◽  
Static Magnetization ◽  
Specific Domain ◽  
Helium Ion

AbstractGlobal Helium ion irradiation can tune the magnetic properties of thin films, notably their magneto-crystalline anisotropy. Helium ion irradiation through nanofabricated masks can been used to produce sub-micron planar magnetic nanostructures of various types. Among these, perpendicularly magnetized dots in a matrix of weaker magnetic anisotropy are of special interest because their quasi-static magnetization reversal is nucleation-free and proceeds by a very specific domain wall injection from the magnetically “soft” matrix, which acts as a domain wall reservoir for the “hard” dot. This guarantees a remarkably weak coercivity dispersion. This new type of irradiation-fabricated magnetic device can also be designed to achieve high magnetic switching speeds, typically below 100 ps at a moderate applied field cost. The speed is obtained through the use of a very high effective magnetic field, and high resulting precession frequencies. During magnetization reversal, the effective field incorporates a significant exchange field, storing energy in the form of a domain wall surrounding a high magnetic anisotropy nanostructure's region of interest. The exchange field accelerates the reversal and lowers the cost in reversal field. Promising applications to magnetic storage are anticipated.

Green synthesis of iron nanoparticles using flower extract of Piliostigma thonningii and their antibacterial activity evaluation

2019 ◽  
Author(s):  
Chem Int
Keyword(s):  
Antibacterial Activity ◽  
Environmental Remediation ◽  
Iron Nanoparticles ◽  
Reduction Process ◽  
Xrd Analysis ◽  
Visible Range ◽  
Magnetic Storage ◽  
Ferrous Chloride ◽  
Flower Extract ◽  
Piliostigma Thonningii

Iron nanoparticles have gained tremendous attention due to their application in magnetic storage media, ferrofluids, biosensors, catalysts, separation processes, environmental remediation and antibacterial activity. In the present paper, iron nanoparticles were synthesized using aqueous flower extract of Piliostigma thonningii, a natural nontoxic herbal infusion. Iron nanoparticles were generated by reaction of ferrous chloride solution with the flower extract. The reductants present in the flower extract acted as reducing and stabilizing agents. UV-vis analysis of the iron nanoparticles showed continuous absorption in the visible range suggesting the iron nanoparticles were amorphous. This was confirmed by X-ray diffraction (XRD) analysis which did not have distinct diffraction peaks. Scanning electron microscopy (SEM) analysis revealed that the synthesized iron nanoparticles were aggregated as irregular clusters with rough surfaces. FT-IR studies showed the functional groups that participated in the bio-reduction process to include a C-H stretch (due to alkane CH3, CH2 or CH), C=O stretch (due to aldehydes), O-H bend (due to tert-alcohol or phenol), C-O stretch (due to aldehydes or phenols) and C-O stretch (due to alcohols) corresponding to absorptions at 2929.00, 1721.53, 1405.19, 1266.31 and 1030.02 cm-1 respectively. The iron nanoparticles showed significant antibacterial activity against Escharichia coli and Staphylococcus aureus suggesting potential antibacterial application.

scholarly journals New advances on Au–magnetic organic hybrid core–shells in MRI, CT imaging, and drug delivery

RSC Advances ◽  
2021 ◽  
Vol 11 (12) ◽  
pp. 6517-6525
Author(s):  
Fatemeh Mohajer ◽  
Ghodsi Mohammadi Ziarani ◽  
Alireza Badiei
Keyword(s):  
Magnetic Resonance Imaging ◽  
Drug Delivery ◽  
Magnetic Nanoparticles ◽  
Targeted Drug Delivery ◽  
Magnetic Storage ◽  
Resonance Imaging ◽  
Organic Hybrid ◽  
Storage Media ◽  
Targeted Drug ◽  
Magnetic Storage Media

Magnetic nanoparticles have been studied for scientific and technological applications such as magnetic storage media, contrast agents for magnetic resonance imaging, biolabelling, separation of biomolecules, and magnetic-targeted drug delivery.

scholarly journals Ultrafast optical manipulation of magnetic order in ferromagnetic materials

2020 ◽  
Vol 7 (1) ◽  
Author(s):  
Chuangtang Wang ◽  
Yongmin Liu
Keyword(s):  
Data Storage ◽  
Optical Switching ◽  
Ultrafast Lasers ◽  
Transport Model ◽  
Magnetic Interaction ◽  
Ferromagnetic Materials ◽  
Magnetic Storage ◽  
Magnetization Dynamics ◽  
Quarter Century ◽  
Ultrafast Optical

Abstract The interaction between ultrafast lasers and magnetic materials is an appealing topic. It not only involves interesting fundamental questions that remain inconclusive and hence need further investigation, but also has the potential to revolutionize data storage technologies because such an opto-magnetic interaction provides an ultrafast and energy-efficient means to control magnetization. Fruitful progress has been made in this area over the past quarter century. In this paper, we review the state-of-the-art experimental and theoretical studies on magnetization dynamics and switching in ferromagnetic materials that are induced by ultrafast lasers. We start by describing the physical mechanisms of ultrafast demagnetization based on different experimental observations and theoretical methods. Both the spin-flip scattering theory and the superdiffusive spin transport model will be discussed in detail. Then, we will discuss laser-induced torques and resultant magnetization dynamics in ferromagnetic materials. Recent developments of all-optical switching (AOS) of ferromagnetic materials towards ultrafast magnetic storage and memory will also be reviewed, followed by the perspectives on the challenges and future directions in this emerging area.

Wear Modeling of Nanometer Thick Protective Coatings

2016 ◽  
Vol 139 (2) ◽  
Author(s):  
Jungkyu Lee ◽  
Youfeng Zhang ◽  
Robert M. Crone ◽  
Narayanan Ramakrishnan ◽  
Andreas A. Polycarpou
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Protective Coatings ◽  
Element Model ◽  
Disk Surface ◽  
Magnetic Storage ◽  
Theoretical Frameworks ◽  
Storage Devices ◽  
Parametric Studies ◽  
Magnetic Storage Devices

Use of nanometer thin films has received significant attention in recent years because of their advantages in controlling friction and wear. There have been significant advances in applications such as magnetic storage devices, and there is a need to explore new materials and develop experimental and theoretical frameworks to better understand nanometer thick coating systems, especially wear characteristics. In this work, a finite element model is developed to simulate the sliding wear between the protruded pole tip in a recording head (modeled as submicrometer radius cylinder) and a rigid asperity on the disk surface. Wear is defined as plastically deformed asperity and material yielding. Parametric studies reveal the effect of the cylindrical asperity geometry, material properties, and contact severity on wear. An Archard-type wear model is proposed, where the wear coefficients are directly obtained through curve fitting of the finite element model, without the use of an empirical coefficient. Limitations of such a model are also discussed.

Resistless Patterning of Magnetic Storage Media Using Ion Projection Structuring

2001 ◽  
Vol 705 ◽  
Author(s):  
A. Dietzel ◽  
R. Berger ◽  
H. Grimm ◽  
C. Schug ◽  
W. H. Bruenger ◽  
...  
Keyword(s):  
Process Development ◽  
Ion Beam ◽  
Silicon On Insulator ◽  
Magnetic Storage ◽  
Magnetic Islands ◽  
Superlattice Structure ◽  
Head Positioning ◽  
Out Of Plane ◽  
Set Up ◽  
The Impact

AbstractCo/Pt thin film multilayers with strong perpendicular anisotropy and out-of-plane coercivities of 5-11 kOe were magnetically altered in areas of local ion beam interaction. The ion irradiations were performed by ion projection through silicon stencil masks fabricated by silicon on insulator (SOI) membrane technology. The ion projector at the Fraunhofer Institute for Silicon Technology (ISiT) was operated at 73 keV ion energy and with a 8.7- fold demagnification. After exposure to 3 × 1014Ar+/ cm2 magnetic islands smaller than 100 nm in diameter were resolved in the Co/Pt multilayersby means of magnetic force microscopy. The impact of different ion species (He+, Ar+ and Xe+) and ion energies (10 – 200 keV) on the multilayer structure was evaluated using Monte Carlo simulations. The ballistic interface intermixing was used to predict magnetic coercivity changes for various irradiation conditions. The simulations revealed that with 73 keV Ar+ and Xe+ ions the irradiation dose could be reduced by a factor of 100 and 400 respectively in comparison to 73 keV He+which was verified in the experiments. X-ray reflectivity measurements confirmed that the Co/Pt superlattice structure is slightly weakened during the irradiation and that the surface smoothness of the media is preserved. Using the Ion Projection Process Development Tool (PDT) at IMS-Vienna concentric data tracks including head positioning servo informations were patterned onto a 1” IBM microdrive™ glass disk which was coated with Co/Pt multilayers. In a single exposure step several tracks within an exposure field of 17 mm in diameter were structured by 2 × 1015He+/ cm2 at 45 keV using a 4- fold demagnification set-up.

Carbon Overcoat Loss From the Surface of a Heat Assisted Magnetic Storage Disk due to Laser Irradiation

2013 ◽  
Author(s):  
Paul M. Jones ◽  
Joachim Ahner ◽  
Christopher L. Platt ◽  
Huan Tang ◽  
Julius Hohlfeld
Keyword(s):  
Curie Temperature ◽  
Laser Power ◽  
Single Point ◽  
Magnetic Layer ◽  
Pump Laser ◽  
Probe Laser ◽  
Magnetic Storage ◽  
Carbon Overcoat ◽  
Fept Alloy ◽  
The Media

A pump-probe experimental technique that incorporated a 527nm wavelength pump laser and a 476nm probe laser was applied to a magnetic storage disk having a magnetic layer comprised of a FePt alloy and coated with a hydrogenated carbon overcoat (COC). The pump laser power was systematically increased while sweeping the applied field with an electromagnet to observe the temperature dependent magnetization, which is proportional to the change in the polarization of the reflected beam. In this way the laser power required to heat the media to the Curie temperature (Tc) was determined, with the Curie temperature of the media determined from a separate magnetometry measurement. Such a single point laser power-to-media temperature calibration allowed the determination of the media temperature over a small laser power range near Tc. The carbon over-coated FePt media was then irradiated for varying durations at temperatures pertinent to a Heat Assisted Magnetic Recording (HAMR) device [1]. The COC surface topography and carbon bonding structure within each irradiated zone was probed with AFM and micro-spot Raman. A subtle, systematic temperature and duration dependent change in the COC was observed. With increasing temperature and duration, the Raman D-peak became increasingly pronounced, signaling an increase of the sp2 (disorder) content in the film in the irradiated region. At incrementally higher temperatures, the loss of the carbon overcoat becomes apparent as a shallow depression in the COC film in the irradiated area. A clearer picture of the possible sensitivity and kinetics of the loss of COC on the HAMR media surface was obtained by measuring its loss over a range of irradiation temperatures and durations. The activation energy and COC loss rate were obtained and a possible mechanism for COC failure-loss was discussed within the bounds of the operating HAMR device [2].

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