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Open Access Nano Express

Growth mechanism and magnon excitation in NiO nanowalls

Ashish Chhaganlal Gandhi1, Chih-Yeh Huang1, Chun Chuen Yang2, Ting Shan Chan3, Chia-Liang Cheng1, Yuan-Ron Ma1 and Sheng Yun Wu1*

Author Affiliations

1 Department of Physics, National Dong Hwa University, Hualien 97401, Taiwan

2 Department of Physics, Chung Yuan Christian University, Chungli 32023, Taiwan

3 National Synchrotron Radiation Research Center, Hsinchu 30076, Taiwan

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Nanoscale Research Letters 2011, 6:485  doi:10.1186/1556-276X-6-485

Published: 8 August 2011

Abstract

The nanosized effects of short-range multimagnon excitation behavior and short-circuit diffusion in NiO nanowalls synthesized using the Ni grid thermal treatment method were observed. The energy dispersive spectroscopy mapping technique was used to characterize the growth mechanism, and confocal Raman scattering was used to probe the antiferromagnetic exchange energy J2 between next-nearest-neighboring Ni ions in NiO nanowalls at various growth temperatures below the Neel temperature. This study shows that short spin correlation leads to an exponential dependence of the growth temperatures and the existence of nickel vacancies during the magnon excitation. Four-magnon configurations were determined from the scattering factor, revealing a lowest state and monotonic change with the growth temperature.

PACS: 75.47.Lx; 61.82.Rx; 75.50.Tt; 74.25.nd; 72.10.Di

Keywords:
magnetic oxides; nanocrystalline materials; confocal Raman scattering; short-circuit diffusion; magnon excitation