| CONDENSED MATTER: ELECTRONIC STRUCTURE, ELECTRICAL, MAGNETIC, AND OPTICAL PROPERTIES |
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Magnetic Relaxation Study on Single Crystals of Ni4 Single-Molecule Magnets |
| LI Yan-Rong1,2, LIU Hai-Qing1, LIU Ying1, SU Shao-Kui1, WANG Yun-Ping1 |
| 1Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 1001902Department of Physics, University of Science and Technology of China, Hefei 230026 |
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| Cite this article: |
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LI Yan-Rong, LIU Hai-Qing, LIU Ying et al 2009 Chin. Phys. Lett. 26 077504 |
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Abstract The ac susceptibility of single crystals of Ni4 single-molecule magnets is measured by a compensation measurement setup. The magnetic relaxation time calculated from the peak of the out-phase component of the susceptibility fits the Arrhenius law well and gives an effective spin-flipping energy barrier of Ueff=7.2K. This value is far below the classical activation energy barrier of U=14K, whereas it is close to the energy gap between the Sz=±4 and Sz=±3 doublets, which indicates that quantum tunneling between the Sz=3 and Sz=-3 states plays a key role in the magnetic relaxation. Therefore the relaxation process combines thermal activation and quantum tunneling. Also we deduce that the blocking temperature of Ni4 single-molecule magnets is lower than 0.3K by extrapolating the relaxation time plot, which ensures that this single-molecule magnet material enters a long-range magnetic ordered state instead of a spin glass state at 0.91K.
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| Keywords:
75.45.+j
61.46.-w
75.20.-g
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Received: 08 May 2009
Published: 02 July 2009
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| PACS: |
75.45.+j
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(Macroscopic quantum phenomena in magnetic systems)
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61.46.-w
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(Structure of nanoscale materials)
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75.20.-g
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(Diamagnetism, paramagnetism, and superparamagnetism)
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[21] Li Y R and Wang Y P (unpublished) |
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