High-frequency millimeter wave absorption of indium-substituted ε-Fe{sub 2}O{sub 3} spherical nanoparticles (invited)

Journal Article · Wed May 07 00:00:00 EDT 2014 · Journal of Applied Physics

DOI:https://doi.org/10.1063/1.4870168· OSTI ID:22273588

Yoshikiyo, Marie; Namai, Asuka ^[1]; Nakajima, Makoto ^[2]; Yamaguchi, Keita; Suemoto, Tohru ^[3]; Ohkoshi, Shin-ichi ^[1]

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1. Department of Chemistry, School of Science, The University of Tokyo 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033 (Japan)
2. Department of Physics, Chiba University 1-33 Yayoicho, Inage Ward, Chiba-shi, Chiba 263-8522 (Japan)
3. Institute for Solid State Physics, The University of Tokyo 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8581 (Japan)

In this work, we prepared indium-substituted ε-iron oxide (ε-In{sub x}Fe{sub 2−x}O{sub 3}) spherical nanoparticles by a combination method of reverse-micelle and sol-gel techniques. The powder X-ray diffraction pattern with Rietveld analysis shows that ε-In{sub x}Fe{sub 2−x}O{sub 3} has an orthorhombic crystal structure (space group: Pna2{sub 1}), and the In{sup 3+} ions mainly replace the Fe{sup 3+} ions at B site among the four nonequivalent Fe{sup 3+} sites (A–D sites). The magnetic measurements show that the coercive field (H{sub c}) at 300 K decreases with increasing x, i.e., H{sub c} = 21.9 kOe (x = 0), 12.2 kOe (x = 0.04), 11.6 kOe (x = 0.09), 7.8 kOe (x = 0.13), and 5.9 kOe (x = 0.18). Millimeter wave absorption was measured by terahertz time-domain spectroscopy, and the decrease of resonance frequency (f{sub r}) is observed, i.e., f{sub r} = 182 GHz (x = 0), 160 GHz (x = 0.04), 143 GHz (x = 0.09), 123 GHz (x = 0.13), and 110 GHz (x = 0.18). This decrease in the f{sub r} value is understood by the decrease of magnetic anisotropy, which is caused by the replacement of Fe{sup 3+} (S = 5/2) with nonmagnetic In{sup 3+} (S = 0) at B site contributing to the magnetic anisotropy.

• OSTI ID: 22273588
• Journal Information: Journal of Applied Physics, Vol. 115, Issue 17; Conference: 55. annual conference on magnetism and magnetic materials, Atlanta, GA (United States), 14-18 Nov 2010; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA); ISSN 0021-8979
• Country of Publication: United States
• Language: English

Related Subjects

75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
ABSORPTION
ABSORPTION SPECTROSCOPY
ANISOTROPY
GHZ RANGE
INDIUM COMPOUNDS
INDIUM IONS
IRON IONS
IRON OXIDES
NANOSTRUCTURES
ORTHORHOMBIC LATTICES
PARTICLES
POWDERS
SOL-GEL PROCESS
X-RAY DIFFRACTION