ISSN:
1573-7357
Source:
Springer Online Journal Archives 1860-2000
Topics:
Physics
Notes:
The 27Al nuclear spin-lattice relaxation times T 1 have been measured in the normal and superconducting states of small aluminum particles with average particle diameters ranging from 170 to 750 ». Experiments were performed in magnetic fields between 0 and 1200 Oe and at temperatures between 0.5 and 4.2 K. The nuclear spin-lattice relaxation rate 1/T 1 at zero and low magnetic fields is characterized by a sum of a Korringa rate (due to conduction-electron spin-flip scattering) and an additional rate, which is attributed to a cross-relaxation process involving nuclei near the particle surfaces. At the highest field (1200 Oe), where the Zeeman energy either dominates in larger particles or plays an important role in smaller particles, measured rates for all three samples are in good agreement with the microscopic theory of Sone. At low fields (H ≤ 150 Oe) our T 1 results, which show a strong field dependence and less effect of superconducting fluctuations near T c, are in disagreement with Sone. We suggest that the theory has overestimated the effects of fluctuations on quasiparticle excitations at these low fields.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00115625
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