Mechanism of magnetization process of island-like L10 FePt films

Li, Guoqing; Takahoshi, H.; Ito, Hirotaka; Washiya, T.; Saito, Hitoshi; Ishio, S.; Shima, T.; Takanashi, Kōki

doi:10.1016/j.jmmm.2004.10.035

Cited by 11 publications

(7 citation statements)

References 15 publications

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“…It would explain the low coercive fields in these films, in spite of their high magnetic anisotropy. Note, such magnetic structure variation was previously observed only in films with significantly different thicknesses 59,60 , implying corresponding structural differences required for the different states of the magnetic domain formation. In our case, the thickness of the films is identical.…”

Section: A Fept Thin Filmsmentioning

confidence: 66%

“…4(a,d)]. Such multiple domain (MD) structure can also be found in the films with the island structure, if the size of the islands exceeds the critical size of the SD islands (∼ 200 nm for the in-plane direction 59,60 ). The demagnetization process of the MD films is dominated by the nucleation of magnetization reversal followed by domain wall displacement, which is energetically favourable without structural pinning for the domain walls.…”

Section: A Fept Thin Filmsmentioning

confidence: 95%

See 1 more Smart Citation

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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Section: A Fept Thin Filmsmentioning

confidence: 66%

Section: A Fept Thin Filmsmentioning

confidence: 95%

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

Golovchanskiy

Pan

Fedoseev

et al. 2014

Applied Surface Science

View full text Add to dashboard Cite

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“…Transmission electron microscopy observations confirmed that the particles are perfect crystals except for some lattice strain [22]. The particles were mostly single-domain with a nominal thickness of t N o20 nm, while the films were continuous for t N 445 nm [19,23,24]. The present work examines the magnetic properties of the films with thicknesses in the range of 25pt N p40 nm, with the aim of investigating the magnetization behavior of assemblies of multi-domain particles.…”

Section: Methodsmentioning

confidence: 88%

“…4. A particle size of 50 nm was chosen to be typical due to the large particle size distribution and the average particle height being higher than the nominal thickness, t N [24]. The horizontal axis (d) denotes the width of the central domain in which the magnetization was opposite to the positive direction of H (see the inset of Fig.…”

Section: Article In Pressmentioning

confidence: 99%

Anomalous magnetization processes and non-symmetrical domain wall displacements in L10 FePt particulate films

Saito

Ishio

et al. 2006

Journal of Magnetism and Magnetic Materials

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“…The magnetization reversal of a magnetically saturated sample is likely to be a nucleation type. The discrete multidomain particles can be easily magnetized through domain wall displacement, but it is hard to demagnetize the magnetically saturated particles, regardless of size or shape [35,36].…”

Section: Experiments and Simulationmentioning

confidence: 99%

Magnetic properties of perpendicularly orientated L10 FePt nanoparticles

Xiang

et al. 2010

Chin. Sci. Bull.

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L1 0 FePt films were deposited on MgO (001) substrates heated to 700°C by magnetron sputtering. Assisted by the misfit of lattice between film and substrate, strong (001) texture was formed. The film at nominal thickness t N = 5 nm was composed of nanoparticles with a size of ~70 nm, and showed a high coercivity of ~105 kOe at 4.2 K. At t N =~50 nm, as the film changed from discontinuous to continuous, the coercivity dropped about one order of magnitude. Micromagnetic simulation implies that the magnetization reversal is a vortex-like nuclear type. The ideal coercivity of a separated single-domain L1 0 FePt nanoparticle with a size of 70 nm× 70 nm× 5 nm is ~121 kOe. This tells us that the experimental coercivity has nearly reached the limit of ideal single crystalline nanoparticles. L1 0 FePt nanoparticle, coercivity, magnetization reversal, magnetic domain Citation: Mo X J, Xiang H, Li G Q, et al. Magnetic properties of perpendicularly orientated L1 0 FePt nanoparticles.Magnetic recording media for data storage is one of the most important applications of magnetic materials due to its nonvolatility and low cost per megabyte. In longitude mode (LMR, longitude magnetic recording), data are recorded by magnetizing a cluster of grains, called as a bit cell. The magnetic interactions between two oppositely magnetized neighbouring bit cells (represent data of "0" and "1", respectively) are repulsive. The areal density beyond 200 Gb/in 2 of LMR media will be limited. By designing an innovative recording mode (named as perpendicular magnetic recording, PMR), magnetic recording media with areal density exceeding 1 Tb/in 2 could be developed [1-7]. In contrast to LMR, the magnetic interactions between two neighbouring "0"and "1" bit cells in PMR media are attractive. Even the magnetization of each discrete grain can represent a bit of data [8]. The magnetization fluctuates randomly because of thermal energy, k B T, where k B is the Boltzmann's constant and T is the temperature. To avoid unstable magnetization due to a phenomenon called as superparamagnetism [9], the materials used in PMR media need to exhibit high uniaxial magnetocrystalline anisotropy energy (K u ). The near-stoichiometric L1 0 phase FePt alloy with K u = 7×10 7 erg/cm 3 has prompted intense research activity and is considered to be one of the most promising candidates for high density PMR media [10][11][12][13], as the magnetization energy barrier in a grain as small as 3 nm is enough to overcome thermal instability [14]. L1 0 FePt has face centered tetragonal (FCT) structure with lattice constants a = b = 0.3905 nm, and c = 0.3735 nm. It can be kept in air without oxidation due to its chemical stability. Its Curie temperature is about 750 K. Bulk FePt alloy synthesized at room temperature nominally adopts its high temperature disordered A1 phase (a random solid solution face centered cubic (FCC) structure,

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Mechanism of magnetization process of island-like L10 FePt films

Cited by 11 publications

References 15 publications

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

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

Anomalous magnetization processes and non-symmetrical domain wall displacements in L10 FePt particulate films

Magnetic properties of perpendicularly orientated L10 FePt nanoparticles

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