Inhomogeneous magnetic phase in Co-Al-O spinel nanocrystals

K. Sato; T. Naka; T. Nakane; D. Rangappa; S. Takami; S. Ohara; T. Adschiri

doi:10.1016/j.jmmm.2013.09.012

Inhomogeneous magnetic phase in Co-Al-O spinel nanocrystals

K. Sato, T. Naka, T. Nakane, D. Rangappa, S. Takami, S. Ohara, T. Adschiri

Advanced Institute for Materials Research (AIMR)

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

3 Citations (Scopus)

Abstract

We report on the crystallographic structure and magnetism of 5-nm Co-Al-O spinel nanocrystals synthesized under supercritical hydrothermal conditions. Structural examination using powder X-ray diffraction and chemical analysis showed the composition of the sample to be Co_0.47Al _2.36O₄ rather than the stoichiometric composition of CoAl₂O₄. The site occupancy of Co on the A-site forming the diamond lattice was 0.47, which is slightly larger than the site percolation limit. Magnetization measurements showed that magnetic clusters emerged below 40 K. At temperatures below 40 K, a Griffiths-phase-like inhomogeneous state appeared in the sample in which magnetic clusters and paramagnetic spins coexisted. The dc-paramagnetic and ac-susceptibilities exhibited an anomaly below 7 K.

Original language	English
Pages (from-to)	161-166
Number of pages	6
Journal	Journal of Magnetism and Magnetic Materials
Volume	350
DOIs	https://doi.org/10.1016/j.jmmm.2013.09.012
Publication status	Published - 2014

Keywords

Antiferromagnetism
Cobalt spinel
Crystal structure
Nanocrystal

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10.1016/j.jmmm.2013.09.012

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@article{01450b00be1d494bae35b329e1b51997,

title = "Inhomogeneous magnetic phase in Co-Al-O spinel nanocrystals",

abstract = "We report on the crystallographic structure and magnetism of 5-nm Co-Al-O spinel nanocrystals synthesized under supercritical hydrothermal conditions. Structural examination using powder X-ray diffraction and chemical analysis showed the composition of the sample to be Co0.47Al 2.36O4 rather than the stoichiometric composition of CoAl2O4. The site occupancy of Co on the A-site forming the diamond lattice was 0.47, which is slightly larger than the site percolation limit. Magnetization measurements showed that magnetic clusters emerged below 40 K. At temperatures below 40 K, a Griffiths-phase-like inhomogeneous state appeared in the sample in which magnetic clusters and paramagnetic spins coexisted. The dc-paramagnetic and ac-susceptibilities exhibited an anomaly below 7 K.",

keywords = "Antiferromagnetism, Cobalt spinel, Crystal structure, Nanocrystal",

author = "K. Sato and T. Naka and T. Nakane and D. Rangappa and S. Takami and S. Ohara and T. Adschiri",

note = "Funding Information: This research was partly supported by Grants-in-Aid for Scientific Research (KAKENHI) from the Japan Society for the Promotion of Science (Grant nos. 21241023 and 25246013 ). We thank The Material Analysis Station of the National Institute for Materials Science for ICP-MS analyses.",

year = "2014",

doi = "10.1016/j.jmmm.2013.09.012",

language = "English",

volume = "350",

pages = "161--166",

journal = "Journal of Magnetism and Magnetic Materials",

issn = "0304-8853",

publisher = "Elsevier",

}

TY - JOUR

T1 - Inhomogeneous magnetic phase in Co-Al-O spinel nanocrystals

AU - Sato, K.

AU - Naka, T.

AU - Nakane, T.

AU - Rangappa, D.

AU - Takami, S.

AU - Ohara, S.

AU - Adschiri, T.

N1 - Funding Information: This research was partly supported by Grants-in-Aid for Scientific Research (KAKENHI) from the Japan Society for the Promotion of Science (Grant nos. 21241023 and 25246013 ). We thank The Material Analysis Station of the National Institute for Materials Science for ICP-MS analyses.

PY - 2014

Y1 - 2014

N2 - We report on the crystallographic structure and magnetism of 5-nm Co-Al-O spinel nanocrystals synthesized under supercritical hydrothermal conditions. Structural examination using powder X-ray diffraction and chemical analysis showed the composition of the sample to be Co0.47Al 2.36O4 rather than the stoichiometric composition of CoAl2O4. The site occupancy of Co on the A-site forming the diamond lattice was 0.47, which is slightly larger than the site percolation limit. Magnetization measurements showed that magnetic clusters emerged below 40 K. At temperatures below 40 K, a Griffiths-phase-like inhomogeneous state appeared in the sample in which magnetic clusters and paramagnetic spins coexisted. The dc-paramagnetic and ac-susceptibilities exhibited an anomaly below 7 K.

AB - We report on the crystallographic structure and magnetism of 5-nm Co-Al-O spinel nanocrystals synthesized under supercritical hydrothermal conditions. Structural examination using powder X-ray diffraction and chemical analysis showed the composition of the sample to be Co0.47Al 2.36O4 rather than the stoichiometric composition of CoAl2O4. The site occupancy of Co on the A-site forming the diamond lattice was 0.47, which is slightly larger than the site percolation limit. Magnetization measurements showed that magnetic clusters emerged below 40 K. At temperatures below 40 K, a Griffiths-phase-like inhomogeneous state appeared in the sample in which magnetic clusters and paramagnetic spins coexisted. The dc-paramagnetic and ac-susceptibilities exhibited an anomaly below 7 K.

KW - Antiferromagnetism

KW - Cobalt spinel

KW - Crystal structure

KW - Nanocrystal

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U2 - 10.1016/j.jmmm.2013.09.012

DO - 10.1016/j.jmmm.2013.09.012

M3 - Article

AN - SCOPUS:84886302669

SN - 0304-8853

VL - 350

SP - 161

EP - 166

JO - Journal of Magnetism and Magnetic Materials

JF - Journal of Magnetism and Magnetic Materials

ER -

Inhomogeneous magnetic phase in Co-Al-O spinel nanocrystals

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Keywords

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