Magnetic properties of annealed core-shell CoPt nanoparticles

Jean Yves Bigot, Hasan Kesserwan, Valérie Halté, Ovidiu Ersen, M. Simona Moldovan, Tae Hee Kim, Jung Tak Jang, Jinwoo Cheon

Research output: Contribution to journalArticle

34 Citations (Scopus)

Abstract

A precise control and understanding of the magnetization dynamics of nanostructures is an important topic in applied nanosciences. Herein, we perform such control by annealing crystalline (Co/core)-(Pt/shell) nanoparticles. Using electron tomography, temperature dependent electron microscopy and time-resolved magneto-optics, we establish a clear correlation between the magnetization dynamics and the crystalline structure of the nanoparticles. For a mild laser annealing (370 K) the Co-Pt nanoparticles keep their core-shell structure and remain superparamagnetic with a blocking temperature T B = 66 K. Their time-resolved reflectivity shows that they are locally organized into a supra-crystalline ordered layer in the region of the laser spot. In contrast, a thermal annealing at higher temperatures (up to 700 K) modifies the structure of the individual nanoparticles into a CoPt crystalline ferromagnetic phase, with T B,anneal = 347 K. Correspondingly, the magneto-crystalline anisotropy of the annealed CoPt nanoparticles increases and their magnetization dynamics displays a motion of precession, characteristic of ferromagnetic nanostructures and which is absent in the superparamagnetic Co-Pt core-shells.

Original languageEnglish
Pages (from-to)1189-1197
Number of pages9
JournalNano letters
Volume12
Issue number3
DOIs
Publication statusPublished - 2012 Mar 14

Fingerprint

Magnetic properties
Nanoparticles
magnetic properties
Crystalline materials
nanoparticles
Magnetization
Annealing
magnetization
Nanostructures
Nanoscience
Magnetooptical effects
annealing
laser annealing
Lasers
magneto-optics
precession
Temperature
Electron microscopy
Tomography
electron microscopy

All Science Journal Classification (ASJC) codes

  • Bioengineering
  • Chemistry(all)
  • Materials Science(all)
  • Condensed Matter Physics
  • Mechanical Engineering

Cite this

Bigot, J. Y., Kesserwan, H., Halté, V., Ersen, O., Moldovan, M. S., Kim, T. H., ... Cheon, J. (2012). Magnetic properties of annealed core-shell CoPt nanoparticles. Nano letters, 12(3), 1189-1197. https://doi.org/10.1021/nl300306a
Bigot, Jean Yves ; Kesserwan, Hasan ; Halté, Valérie ; Ersen, Ovidiu ; Moldovan, M. Simona ; Kim, Tae Hee ; Jang, Jung Tak ; Cheon, Jinwoo. / Magnetic properties of annealed core-shell CoPt nanoparticles. In: Nano letters. 2012 ; Vol. 12, No. 3. pp. 1189-1197.
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Bigot, JY, Kesserwan, H, Halté, V, Ersen, O, Moldovan, MS, Kim, TH, Jang, JT & Cheon, J 2012, 'Magnetic properties of annealed core-shell CoPt nanoparticles', Nano letters, vol. 12, no. 3, pp. 1189-1197. https://doi.org/10.1021/nl300306a

Magnetic properties of annealed core-shell CoPt nanoparticles. / Bigot, Jean Yves; Kesserwan, Hasan; Halté, Valérie; Ersen, Ovidiu; Moldovan, M. Simona; Kim, Tae Hee; Jang, Jung Tak; Cheon, Jinwoo.

In: Nano letters, Vol. 12, No. 3, 14.03.2012, p. 1189-1197.

Research output: Contribution to journalArticle

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AU - Kim, Tae Hee

AU - Jang, Jung Tak

AU - Cheon, Jinwoo

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Bigot JY, Kesserwan H, Halté V, Ersen O, Moldovan MS, Kim TH et al. Magnetic properties of annealed core-shell CoPt nanoparticles. Nano letters. 2012 Mar 14;12(3):1189-1197. https://doi.org/10.1021/nl300306a