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物質創成科学研究科 / Graduate School of Materials Science >
Please use this identifier to cite or link to this item:
http://hdl.handle.net/10061/6657
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| Title: | Controlled magnetic properties of Ni nanoparticles embedded in polyimide films |
| Authors: | Tomita, Satoshi
Joensson, Petra E.
Akamatsu, Kensuke
Nawafune, Hidemi
Takayama, Hajime |
| Issue Date: | Nov-2007 |
| Publisher: | American Physical Society |
| Journal Title: | PHYSICAL REVIEW B |
| Volume: | 76 |
| Issue: | 17 |
| Article Number: | 174432 |
| Abstract: | We have studied the magnetic properties of Ni nanoparticles incorporated in polyimide films using dc- and ac-magnetization measurements. Transmission electron microscopy images reveal that both the mean particle diameter (d_ave) and the volume fraction of particles (η_ave) in the composite layer can be controlled independently. In a series of samples with fixed d_ave, the system with the lowest η_ave behaves magnetically as an ensemble of noninteracting superparamagnets. With increasing η_ave, typical signatures of the dipole-dipole interparticle interaction, such as an enhanced blocking temperature, are observed. In dense systems, with a particle concentration above the threshold for geometrical percolation, the magnetic response is ferromagnetic due to the exchange interaction between particles in direct contact. |
| URI: | http://hdl.handle.net/10061/6657 |
| ISSN: | 1098-0121 |
| Rights: | Copyright (C) 2007 American Physical Society. |
| Text Version: | publisher |
| Publisher DOI: | 10.1103/PhysRevB.76.174432 |
| Appears in Collections: | 物質創成科学研究科 / Graduate School of Materials Science
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