High K/sub u/ materials approach to 100 Gbits/in/sup 2/

Weller, D.; Möser, Andreas; Folks, L.; Best, M.E.; Li, Wen; Toney, Michael F.; Schwickert, M. M.; Thiele, Jan-Ulrich; Doerner, M.

doi:10.1109/20.824418

Cited by 1,344 publications

(682 citation statements)

References 40 publications

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“…In the ordered or partially ordered states the alloys display a unique combination of high values of saturation magnetization (l 0 M s = 1.0-1.37 T), constant of magnetocrystalline anisotropy (R % 10 6 -10 7 J m À1 ), magneto-optical characteristics, deformation and corrosion-resistant properties. This combination offers the possibility of using the above alloys as thin-film media for high-density recording and storage of information or as permanent magnets for special purposes [3].…”

Section: Introductionmentioning

confidence: 99%

Discovery of metastable tetragonal disordered phase upon phase transitions in the equiatomic nanostructured FePd alloy

et al. 2013

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Specific features of the phase transformation A1 ! L1 0 (space groups Fm3m and P4/mmm, respectively) in single crystals of the equiatomic alloy FePd subjected to annealings both in the absence and in the presence of external uniaxial load, as well as in polycrystalline samples that had undergone severe plastic deformation via high-pressure torsion and subsequent annealing, have been studied. An investigation of the single crystals in a nanostructured state formed at different stages of ordering annealing was performed using optical polarization, thermomagnetic and transmission electron microscopy (TEM) methods. The nanostructured state of the polycrystalline samples FePd after deformation of both disordered and ordered FePd alloys and subsequent annealing was examined with the help of TEM and X-ray techniques. The results obtained were analyzed based on the known concepts of the symmetry theory of phase transitions. It was concluded that the atomic ordering in the FePd alloys is preceded by the formation of a ferroelastic disordered bodycentered tetragonal phase with the structural type A6 and the space group I4/mmm. Experimental data that evidence the existence of a tetragonal disordered phase both in the single crystals and in the polycrystalline samples of FePd after severe plastic deformation and subsequent annealing are reported. Thus, the A1 M A6 M L1 0 phase transformation represents a combination of different types of phase transitions such as cooperative displacement A1 M A6 and ordering A6 M L1 0 of atoms.

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Section: Introductionmentioning

confidence: 99%

Discovery of metastable tetragonal disordered phase upon phase transitions in the equiatomic nanostructured FePd alloy

et al. 2013

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“…1,2 To maintain both a sufficient SNR and high bit density, the volume of the individual grains that constitute a given bit must approach the superparamagnetic limit. While high anisotropy ͑K u ͒ materials, such as L1 0 FePt alloys, 3 would dramatically improve thermal stability, the magnetic fields required for switching such a high K u bit far exceed the capabilities of the write head. Tilted, 4,5 and exchange coupled composite ͑ECC͒ media, 6 as well as heat-assisted magnetic recording, 7 and microwave-assisted magnetic recording techniques, 8 have been proposed to lower the necessary writing field.…”

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confidence: 99%

Continuously graded anisotropy in single (Fe53Pt47)100−xCux films

Zha

Dumas

Fang

et al. 2010

Applied Physics Letters

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We report on continuously graded anisotropy. During deposition, a compositional gradient is achieved by varying the Cu concentration from Cu-rich (Fe53Pt47)70Cu30 to Cu-free Fe53Pt47. The anisotropy gradient is then realized after annealing using the composition dependence of the low-anisotropy (A1) to high-anisotropy (L10) ordering temperature. The critical role of the annealing temperature on the resultant anisotropy gradient is investigated. Magnetic measurements support the creation of an anisotropy gradient in properly annealed films which exhibit both a reduced coercivity and moderate thermal stability. These results demonstrate that an anisotropy gradient can be realized, and tailored, in single continuous films without the need for multilayers.

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“…These applications become possible due to the film ability to form thermally stable islands (or grains) down to a few nanometers 38,40,41 (boosting recording density 42 ), their high magnetic anisotropy, very high coercivity (exceeding 10 T) 1 and magnetic energy product, the out-of-plane magnetization, and high corrosion resistance. The strong magnetic properties of the films can also be employed for the compensation of applied magnetic field induced effects 39 in certain architectures combining ferromagnets and superconductors 43,44 .…”

Section: Introductionmentioning

confidence: 99%

Significant tunability of thin film functionalities enabled by manipulating magnetic and structural nano-domains

Golovchanskiy

Pan

Fedoseev

et al. 2014

Applied Surface Science

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The influence of laser frequency on the structure and physical properties of thin films grown by pulsed laser deposition has been studied. Different types of thin films, hard ferromagnetic FePt L10 and quasi-single crystal superconducting YBa2Cu3O7 (YBCO), have been used for demonstration of the effect. Significant structural modifications have been obtained for the films with similar thicknesses. These modifications are shown to dramatically control their corresponding properties, providing an instrumental ability for tuning the practical characteristics of the films by changing the laser frequency of their deposition. In particular, 20-fold increase of coercive field and modification of demagnetization mechanism are obtained for FePt films by varying the frequency from 1 Hz to 6 Hz. Over a similar frequency range, a strong dependence on the laser frequency is discovered for the YBCO films for the critical current density behavior as a function of the applied magnetic field [ Jc(Ba)] with the unexpected reversal of Jc(Ba) curves with temperature. The mechanisms of structure modifications and corresponding property variations are proposed. The influence of laser frequency on the structure and physical properties of thin films grown by pulsed laser deposition has been studied. Different types of thin films, hard ferromagnetic FePt L10 and quasi-single crystal superconducting YBa2Cu3O7 (YBCO), have been used for demonstration of the effect. Significant structural modifications have been obtained for the films with similar thicknesses. These modifications are shown to dramatically control their corresponding properties, providing an instrumental ability for tuning the practical characteristics of the films by changing the laser frequency of their deposition. In particular, 20-fold increase of coercive field and modification of demagnetization mechanism are obtained for FePt films by varying the frequency from 1 Hz to 6 Hz. Over a similar frequency range, a strong dependence on the laser frequency is discovered for the YBCO films for the critical current density behaviour as a function of the applied magnetic field [Jc(Ba)] with the unexpected reversal of Jc(Ba) curves with temperature. The mechanisms of structure modifications and corresponding property variations are proposed.

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High K/sub u/ materials approach to 100 Gbits/in/sup 2/

Cited by 1,344 publications

References 40 publications

Discovery of metastable tetragonal disordered phase upon phase transitions in the equiatomic nanostructured FePd alloy

Discovery of metastable tetragonal disordered phase upon phase transitions in the equiatomic nanostructured FePd alloy

Continuously graded anisotropy in single (Fe53Pt47)100−xCux films

Significant tunability of thin film functionalities enabled by manipulating magnetic and structural nano-domains

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