Spin dynamics in highly polarized silver at negative absolute temperatures

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Journal Title
Journal ISSN
Volume Title
School of Science | A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
Date
1992
Major/Subject
Mcode
Degree programme
Language
en
Pages
2196-2200
Series
Physical Review B, Volume 45, Issue 5
Abstract
We have studied the spin dynamics of highly polarized silver nuclei at negative absolute temperatures up to inverted polarizations p≃-70%. The measured NMR spectra at B=0.4 and 0.8 mT display a clear inverted suppression-enhancement effect, arising from an interaction between the two spin species, 107Ag and 109Ag. The averaged interaction-field description accounts well for the intensity ratio of the isotopic NMR lines. The frequency difference of the absorption maxima has been used to study the merging and repulsion of the NMR modes at large negative polarizations. At B=0.2 mT, our spectra display only a single exchange-merged line, indicating that the two isotopes act as like spins. The transition from a single NMR line to two separate lines proceeds in a similar fashion as at positive temperatures. No effects attributable to the tendency of ferromagnetic alignment of spins at T<0 were observed.
Description
Keywords
spin dynamics, polarized silver, negative absolute temperatures
Other note
Citation
Hakonen, Pertti J. & Nummila, K. K. & Vuorinen, R. T. 1992. Spin dynamics in highly polarized silver at negative absolute temperatures. Physical Review B. Volume 45, Issue 5. 2196-2200. ISSN 0163-1829 (printed). DOI: 10.1103/physrevb.45.2196