Susceptibility and relaxation measurements on rhodium metal at positive and negative spin temperatures in the nanokelvin range

Autor: W. Yao, R. T. Vuorinen, Pertti Hakonen, Olli V. Lounasmaa
Rok vydání: 1995
Předmět:
Zdroj: Journal of Low Temperature Physics. 98:449-487
ISSN: 1573-7357
0022-2291
DOI: 10.1007/bf00752278
Popis: We have measured the susceptibility of polycrystalline rhodium foils, down to nuclear spin temperaturesT = 280 pK and “up” toT = −750 pK. AtT > 0, the static susceptibility follows the antiferromagnetic Curie-Weiss law with θ = −1.8±0.3 nK. AtT < 0, the expected ferromagnetic behavior in the vicinity ofT = −0 changes into antiferromgnetic tendency around −6 nK. If only nearest and next nearest neighbor interactions are assumed, our data yieldJn/h = −17±3 Hz andJnnn/h = 10±3 Hz for the exchange interaction coefficients. We have also investigated the field and polarization dependence of the spin-lattice relaxation time τ1 at positive and negative nanokelvin temperatures; surprisingly τ1 is longer whenT< 0. Infields below 1 mT, the Korringa constant shows a strong decrease, which becomes more pronounced as the conduction electron temperature decreases. Observed behavior is consistent with conduction electrons scattering from magnetic impurities, provided that the impurity-induced contribution to spin-lattice relaxation is proportional to the inverse of the nuclear spin temperature in small fields.
Databáze: OpenAIRE
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