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Title: Ledge-type Co/L1{sub 0}-FePt exchange-coupled composites

Abstract

FePt-based exchange-coupled composites consisting of a magnetically hard L1{sub 0}-FePt phase exchange-coupled with a soft ferromagnetic material are promising candidates for future ultra-high density (>1 Tbit/in{sup 2}) perpendicular magnetic recording media, also being of interest for other applications including spin torque oscillators and micro-electro-mechanical systems, among others. In this paper, the effect of the thickness of a soft Co layer (3 < th{sub Co} < 20 nm) on the magnetic behavior of ledge-type fcc(100)-Co/L1{sub 0}(001)-FePt composites deposited on an MgO (100) substrate is systematically studied by combining morpho-structural analyses and angular magnetization measurements. Starting from a film consisting of isolated L1{sub 0}(001)–FePt islands, the ledge-type structure was obtained by depositing a Co layer that either covered the FePt islands or filled-up the inter-island region, gradually forming a continuous layer with increasing Co thickness. A perpendicular anisotropy was maintained up to th{sub Co} ∼ 9.5 nm and a significant reduction in the coercivity (about 50% for th{sub Co} ∼ 3 nm) with the increase in th{sub Co} was observed, indicating that, by coupling hard FePt and soft Co phases in a ledge-type configuration, the writability can be greatly improved. Recoil loops' measurements confirmed the exchange-coupled behavior, reinforcing a potential interest in these systems formore » future magnetic recording media.« less

Authors:
; ;  [1]; ;  [2];  [3]; ; ; ; ;  [4]
  1. Institute of Nanoscience and Nanotechnology, NCSR Demokritos, Athens 15310 (Greece)
  2. Department of Physics, University of Delaware, Newark, Delaware 19716 (United States)
  3. SIMAU, Università Politecnica delle Marche, via Brecce Bianche, Ancona (Italy)
  4. ISM-CNR, Area della Ricerca RM1, Via Salaria Km 29,300, P.B. 10-00015, Monterotondo Scalo, Roma (Italy)
Publication Date:
OSTI Identifier:
22596809
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Applied Physics; Journal Volume: 119; Journal Issue: 23; Other Information: (c) 2016 Author(s); Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; 75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; ANISOTROPY; COERCIVE FORCE; DENSITY; DEPOSITS; FCC LATTICES; FERROMAGNETIC MATERIALS; FILMS; IRON COMPOUNDS; LAYERS; MAGNESIUM OXIDES; MAGNETIZATION; OSCILLATORS; PLATINUM COMPOUNDS; RECOILS; SPIN; SUBSTRATES; THICKNESS; TORQUE

Citation Formats

Speliotis, Th., Giannopoulos, G., Niarchos, D., Li, W. F., Hadjipanayis, G., Barucca, G., Agostinelli, E., Laureti, S., Peddis, D., Testa, A. M., and Varvaro, G., E-mail: gaspare.varvaro@ism.cnr.it. Ledge-type Co/L1{sub 0}-FePt exchange-coupled composites. United States: N. p., 2016. Web. doi:10.1063/1.4953766.
Speliotis, Th., Giannopoulos, G., Niarchos, D., Li, W. F., Hadjipanayis, G., Barucca, G., Agostinelli, E., Laureti, S., Peddis, D., Testa, A. M., & Varvaro, G., E-mail: gaspare.varvaro@ism.cnr.it. Ledge-type Co/L1{sub 0}-FePt exchange-coupled composites. United States. doi:10.1063/1.4953766.
Speliotis, Th., Giannopoulos, G., Niarchos, D., Li, W. F., Hadjipanayis, G., Barucca, G., Agostinelli, E., Laureti, S., Peddis, D., Testa, A. M., and Varvaro, G., E-mail: gaspare.varvaro@ism.cnr.it. 2016. "Ledge-type Co/L1{sub 0}-FePt exchange-coupled composites". United States. doi:10.1063/1.4953766.
@article{osti_22596809,
title = {Ledge-type Co/L1{sub 0}-FePt exchange-coupled composites},
author = {Speliotis, Th. and Giannopoulos, G. and Niarchos, D. and Li, W. F. and Hadjipanayis, G. and Barucca, G. and Agostinelli, E. and Laureti, S. and Peddis, D. and Testa, A. M. and Varvaro, G., E-mail: gaspare.varvaro@ism.cnr.it},
abstractNote = {FePt-based exchange-coupled composites consisting of a magnetically hard L1{sub 0}-FePt phase exchange-coupled with a soft ferromagnetic material are promising candidates for future ultra-high density (>1 Tbit/in{sup 2}) perpendicular magnetic recording media, also being of interest for other applications including spin torque oscillators and micro-electro-mechanical systems, among others. In this paper, the effect of the thickness of a soft Co layer (3 < th{sub Co} < 20 nm) on the magnetic behavior of ledge-type fcc(100)-Co/L1{sub 0}(001)-FePt composites deposited on an MgO (100) substrate is systematically studied by combining morpho-structural analyses and angular magnetization measurements. Starting from a film consisting of isolated L1{sub 0}(001)–FePt islands, the ledge-type structure was obtained by depositing a Co layer that either covered the FePt islands or filled-up the inter-island region, gradually forming a continuous layer with increasing Co thickness. A perpendicular anisotropy was maintained up to th{sub Co} ∼ 9.5 nm and a significant reduction in the coercivity (about 50% for th{sub Co} ∼ 3 nm) with the increase in th{sub Co} was observed, indicating that, by coupling hard FePt and soft Co phases in a ledge-type configuration, the writability can be greatly improved. Recoil loops' measurements confirmed the exchange-coupled behavior, reinforcing a potential interest in these systems for future magnetic recording media.},
doi = {10.1063/1.4953766},
journal = {Journal of Applied Physics},
number = 23,
volume = 119,
place = {United States},
year = 2016,
month = 6
}
  • Two-phase nanostructures of hard L1{sub 0}-ordered FePt and soft iron-rich fcc Fe-Pt are investigated experimentally and by model calculations. The Fe-Pt thin films were produced by epitaxial co-sputtering onto MgO and have a thickness of about 10 nm. They form two-phase dots that cover a large fraction of the surface but are separated from each other. X-ray diffraction and TEM show that the c-axis of the phase FePt is aligned in the direction normal to the film plane. The experimental and theoretical hysteresis loops indicate archetypical exchange coupling, and excellent magnetic properties are obtained. The largest values of coercivity, saturationmore » magnetization, and nominal energy product obtained in the samples studied are 51 kOe, 1287 emu/cc, and 54 MGOe, respectively.« less
  • The interfacial structure of Ni$sub 3$Al--Ni$sub 3$Nb directionally solidified eutectic composites has been investigated by transmission electron microscopy. These interfaces contain at least three distinguishable arrays of features. Two of the arrays, misfit dislocations, have been discussed previously by Nakagawa and Weatherly. The third set, ledges which can fulfill both structural and kinetic growth functions, may interact with the dislocation arrays through strain-energy mechanisms. The interaction is manifested both as a local alteration of the line vector of the dislocation in certain circumstances, and as a change in the response of the dislocation image to +- anti g electron- microscopemore » image-contrast experiments. A simple model of the strain field of a ledge based on that of an edge dislocation is formulated to rationalize the behavior of a misfit dislocation lying in close proximity to a ledge. The interaction of ledges and dislocation segments is expected to have significance in physical processes of practical interest such as production of matrix slip dislocations, misfit dislocation rearrangement, boundary sliding, and coarsening. These processes are discussed. (auth)« less
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  • Exchange coupled hard/soft MnBi/Fe–Co core/shell structured composites were synthesized using a magnetic self-assembly process. MnBi particles were prepared by arc-melting, and Fe–Co nanoparticles were synthesized by an oleic acid assisted chemical reduction method. Grinding a mixture of micron-sized MnBi and Fe–Co nanoparticles in hexane resulted in MnBi/Fe–Co core/shell structured composites. The MnBi/Fe–Co (95/5 wt%) composites showed smooth magnetic hysteresis loops, enhanced remanent magnetization, and positive values in the ΔM curve, indicating exchange coupling between MnBi and Fe–Co particles. - Graphical abstract: Both MnBi and Fe–Co particles were dispersed in hexane for grinding. Because of the oleic acid used during themore » Fe–Co nanoparticle synthesis, they could be well dispersed in hexane. During the grinding, the size of MnBi particles was decreased, hexane was evaporated, and the Fe–Co nanoparticles were concentrated in the solvent and magnetically attracted by MnBi particles, forming a core/shell structure. - Highlights: • Exchange coupled MnBi/Fe–Co composites are synthesized through magnetic selfassembly. • Magnetic exchange coupling is demonstrated by smooth magnetic hysteresis loops, enhanced remanent magnetization, and dominant positive peak in the ΔM curve. • The experimental results in magnetic properties are close to the theoretical calculation results.« less
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