Electron holography of core-shell Co/CoO spherical nanocrystals

Youhui Gao; Daisuke Shindo; Yuping Bao; Kannan Krishnan

doi:10.1063/1.2747052

Electron holography of core-shell Co/CoO spherical nanocrystals

Youhui Gao, Daisuke Shindo, Yuping Bao, Kannan Krishnan

Center for Advanced Microscopy and Spectroscopy

Research output: Contribution to journal › Article › peer-review

11 Citations (Scopus)

Abstract

Phase profiles of core-shell CoCoO nanocrystals are imaged using off-axis electron holography. Contributions of mean inner potential and magnetic induction to the phase shift are extracted, respectively, to quantitatively characterize the nanocrystal geometry and magnetic spin arrangement in a self-assembled nanocrystal chain. It is also found that the spin of 11 nm diameter Co core encapsulated with 5-nm -thick CoO shell remains stable even at an elevated temperature of 200 °C, indicating that the magnetically thermal stability of cobalt nanocrystals is remarkably improved due to the exchange coupling between the ferromagnetic core and antiferromagnetic shell.

Original language	English
Article number	233105
Journal	Applied Physics Letters
Volume	90
Issue number	23
DOIs	https://doi.org/10.1063/1.2747052
Publication status	Published - 2007

ASJC Scopus subject areas

Physics and Astronomy (miscellaneous)

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10.1063/1.2747052

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title = "Electron holography of core-shell Co/CoO spherical nanocrystals",

abstract = "Phase profiles of core-shell CoCoO nanocrystals are imaged using off-axis electron holography. Contributions of mean inner potential and magnetic induction to the phase shift are extracted, respectively, to quantitatively characterize the nanocrystal geometry and magnetic spin arrangement in a self-assembled nanocrystal chain. It is also found that the spin of 11 nm diameter Co core encapsulated with 5-nm -thick CoO shell remains stable even at an elevated temperature of 200 °C, indicating that the magnetically thermal stability of cobalt nanocrystals is remarkably improved due to the exchange coupling between the ferromagnetic core and antiferromagnetic shell.",

author = "Youhui Gao and Daisuke Shindo and Yuping Bao and Kannan Krishnan",

note = "Funding Information: One of the authors (Y.G.) gratefully acknowledges support from the 21st century COE program of Materials Research Center, Tohoku University. Work at the University of Washington was supported by NSF/DMR under Grant Nos. 0203069 and 0501421 and by the Campbell Endowment. Another author (Y.B.) acknowledges partial support from UW/PNNL Joint Institute of Nanoscience. ",

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T1 - Electron holography of core-shell Co/CoO spherical nanocrystals

AU - Gao, Youhui

AU - Shindo, Daisuke

AU - Bao, Yuping

AU - Krishnan, Kannan

N1 - Funding Information: One of the authors (Y.G.) gratefully acknowledges support from the 21st century COE program of Materials Research Center, Tohoku University. Work at the University of Washington was supported by NSF/DMR under Grant Nos. 0203069 and 0501421 and by the Campbell Endowment. Another author (Y.B.) acknowledges partial support from UW/PNNL Joint Institute of Nanoscience.

PY - 2007

Y1 - 2007

N2 - Phase profiles of core-shell CoCoO nanocrystals are imaged using off-axis electron holography. Contributions of mean inner potential and magnetic induction to the phase shift are extracted, respectively, to quantitatively characterize the nanocrystal geometry and magnetic spin arrangement in a self-assembled nanocrystal chain. It is also found that the spin of 11 nm diameter Co core encapsulated with 5-nm -thick CoO shell remains stable even at an elevated temperature of 200 °C, indicating that the magnetically thermal stability of cobalt nanocrystals is remarkably improved due to the exchange coupling between the ferromagnetic core and antiferromagnetic shell.

AB - Phase profiles of core-shell CoCoO nanocrystals are imaged using off-axis electron holography. Contributions of mean inner potential and magnetic induction to the phase shift are extracted, respectively, to quantitatively characterize the nanocrystal geometry and magnetic spin arrangement in a self-assembled nanocrystal chain. It is also found that the spin of 11 nm diameter Co core encapsulated with 5-nm -thick CoO shell remains stable even at an elevated temperature of 200 °C, indicating that the magnetically thermal stability of cobalt nanocrystals is remarkably improved due to the exchange coupling between the ferromagnetic core and antiferromagnetic shell.

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