Observation of nuclear ferromagnetic ordering in silver at negative nanokelvin temperatures

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Ā© 1992 American Physical Society (APS). This is the accepted version of the following article: Hakonen, Pertti J. & Nummila, K. K. & Vuorinen, R. T. & Lounasmaa, O. V. 1992. Observation of nuclear ferromagnetic ordering in silver at negative nanokelvin temperatures. Physical Review Letters. Volume 68, Issue 3. 365-368. ISSN 0031-9007 (printed). DOI: 10.1103/physrevlett.68.365, which has been published in final form at http://journals.aps.org/prl/abstract/10.1103/PhysRevLett.68.365.
Journal Title
Journal ISSN
Volume Title
School of Science | A1 AlkuperƤisartikkeli tieteellisessƤ aikakauslehdessƤ
Date
1992
Major/Subject
Mcode
Degree programme
Language
en
Pages
365-368
Series
Physical Review Letters, Volume 68, Issue 3
Abstract
The ferromagnetically ordered state in the nuclear spin system of silver has been reached at negative absolute temperatures by adiabatic nuclear demagnetization at entropies below 0.82 ln2. The ordering, caused by the antiferromagnetic Ruderman-Kittel interaction, was observed below -1.9 nK as a saturation of susceptibility close to -1 and as an increase of the NMR frequencies. Comparison with recent mean-field calculations by Viertiƶ and Oja suggests a domain configuration. The phase diagram of silver nuclei at T<0 is outlined in the magnetic field versus entropy plane.
Description
Keywords
nuclear magnetism, ferromagnetic ordering, negative temperatures
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Citation
Hakonen, Pertti J. & Nummila, K. K. & Vuorinen, R. T. & Lounasmaa, O. V. 1992. Observation of nuclear ferromagnetic ordering in silver at negative nanokelvin temperatures. Physical Review Letters. Volume 68, Issue 3. 365-368. ISSN 0031-9007 (printed). DOI: 10.1103/physrevlett.68.365