Spin dynamics in highly polarized silver at negative absolute temperatures
School of Science | A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
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Physical Review B, Volume 45, Issue 5
AbstractWe 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.
spin dynamics, polarized silver, negative absolute temperatures
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