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Title: Experimental evidence for the formation of CoFe2C phase with colossal magnetocrystalline-anisotropy

Abstract

Attainment of magnetic order in nanoparticles at room temperature is an issue of critical importance for many different technologies. For ordinary ferromagnetic materials, a reduction in size leads to decreased magnetic anisotropy and results in superparamagnetic relaxations. If, instead, anisotropy could be enhanced at reduced particle sizes, then it would be possible to attain stable magnetic order at room temperature. Herein, we provide experimental evidence substantiating the synthesis of a cobalt iron carbide phase (CoFe2C) of nanoparticles. Structural characterization of the CoFe2C carbide phase was performed by transmission electron microscopy, electron diffraction and energy electron spectroscopy. X-ray diffraction was also performed as a complimentary analysis. Magnetic characterization of the carbide phase revealed a blocking temperature, TB, of 790K for particles with a domain size as small as 5 +/- 1 nm. The particles have magnetocrystalline anisotropy of 4.662 +/- 10 6 J/m(3), which is ten times larger than that of Co nanoparticles. Such colossal anisotropy leads to thermally stable long range magnetic order. Moreover, the thermal stability constant is much larger than that of the commonly used FePt nanoparticles. With thermal stability and colossal anisotropy, the CoFe2C nanoparticles have huge potential for enhanced magnetic data storage devices. (C) 2015 AIPmore » Publishing LLC.« less

Authors:
; ; ; ; ;
Publication Date:
Sponsoring Org.:
USDOE Advanced Research Projects Agency - Energy (ARPA-E)
OSTI Identifier:
1211351
DOE Contract Number:  
1574-1674
Resource Type:
Journal Article
Journal Name:
Applied Physics Letters
Additional Journal Information:
Journal Volume: 106; Journal Issue: 21; Journal ID: ISSN 0003-6951
Country of Publication:
United States
Language:
English

Citation Formats

El-Gendy, AA, Bertino, M, Clifford, D, Qian, MC, Khanna, SN, and Carpenter, EE. Experimental evidence for the formation of CoFe2C phase with colossal magnetocrystalline-anisotropy. United States: N. p., 2015. Web. doi:10.1063/1.4921789.
El-Gendy, AA, Bertino, M, Clifford, D, Qian, MC, Khanna, SN, & Carpenter, EE. Experimental evidence for the formation of CoFe2C phase with colossal magnetocrystalline-anisotropy. United States. doi:10.1063/1.4921789.
El-Gendy, AA, Bertino, M, Clifford, D, Qian, MC, Khanna, SN, and Carpenter, EE. Mon . "Experimental evidence for the formation of CoFe2C phase with colossal magnetocrystalline-anisotropy". United States. doi:10.1063/1.4921789.
@article{osti_1211351,
title = {Experimental evidence for the formation of CoFe2C phase with colossal magnetocrystalline-anisotropy},
author = {El-Gendy, AA and Bertino, M and Clifford, D and Qian, MC and Khanna, SN and Carpenter, EE},
abstractNote = {Attainment of magnetic order in nanoparticles at room temperature is an issue of critical importance for many different technologies. For ordinary ferromagnetic materials, a reduction in size leads to decreased magnetic anisotropy and results in superparamagnetic relaxations. If, instead, anisotropy could be enhanced at reduced particle sizes, then it would be possible to attain stable magnetic order at room temperature. Herein, we provide experimental evidence substantiating the synthesis of a cobalt iron carbide phase (CoFe2C) of nanoparticles. Structural characterization of the CoFe2C carbide phase was performed by transmission electron microscopy, electron diffraction and energy electron spectroscopy. X-ray diffraction was also performed as a complimentary analysis. Magnetic characterization of the carbide phase revealed a blocking temperature, TB, of 790K for particles with a domain size as small as 5 +/- 1 nm. The particles have magnetocrystalline anisotropy of 4.662 +/- 10 6 J/m(3), which is ten times larger than that of Co nanoparticles. Such colossal anisotropy leads to thermally stable long range magnetic order. Moreover, the thermal stability constant is much larger than that of the commonly used FePt nanoparticles. With thermal stability and colossal anisotropy, the CoFe2C nanoparticles have huge potential for enhanced magnetic data storage devices. (C) 2015 AIP Publishing LLC.},
doi = {10.1063/1.4921789},
journal = {Applied Physics Letters},
issn = {0003-6951},
number = 21,
volume = 106,
place = {United States},
year = {2015},
month = {5}
}