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Title
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Ultralow blocking temperature and breakdown of the giant spin model in -doped nanoparticles
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Author
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Abstract
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| The magnetization of luminescent Er3+-doped PbF2 nanoparticles (formula Er0.3Pb0.7F2.3) has been studied. Despite the high concentration of the doping Er3+ ions and relatively large size (8 nm) of these nanoparticles we have found no deviation between field-cooled and zero-field-cooled magnetization curves down to T=0.35 K, which points out an ultralow blocking temperature for the reversal of magnetization. We also have found strongly deviating magnetization curves M(H/T) for different temperatures T. These results altogether show that the investigated nanoparticles are not superparamagnetic, but rather each Er3+ ion in these nanoparticles is found in a paramagnetic state down to very low temperatures, which implies the breakdown of the Néel-Brown giant spin model in the case of these nanoparticles. Calculations of magnetization within a paramagnetic model of noninteracting Er3+ ions completely support this conclusion. Due to the ultralow blocking temperature, these nanoparticles have a potential for magnetic field-induced nanoscale refrigeration with an option of their optical localization and temperature control. |
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Language
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English
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Source (journal)
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Physical review : B : condensed matter and materials physics. - Lancaster, Pa, 1998 - 2015
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Publication
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Lancaster, Pa
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2010
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ISSN
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1098-0121
[print]
1550-235X
[online]
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DOI
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10.1103/PHYSREVB.82.094421
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Volume/pages
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82
:9
(2010)
, p. 094421,1-094421,8
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Article Reference
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094421
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ISI
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000281773300005
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Medium
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E-only publicatie
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Full text (Publisher's DOI)
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Full text (open access)
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