Electron spin-lattice relaxation in noncommon metals YBa2Cu3Ox and Rb1C60

Citation
Va. Atsarkin et al., Electron spin-lattice relaxation in noncommon metals YBa2Cu3Ox and Rb1C60, APPL MAGN R, 15(3-4), 1998, pp. 323-331
Citations number
18
Categorie Soggetti
Spectroscopy /Instrumentation/Analytical Sciences
Journal title
APPLIED MAGNETIC RESONANCE
ISSN journal
09379347 → ACNP
Volume
15
Issue
3-4
Year of publication
1998
Pages
323 - 331
Database
ISI
SICI code
0937-9347(1998)15:3-4<323:ESRINM>2.0.ZU;2-J
Abstract
Using an original modulation technique, the electron spin-lattice relaxatio n have been investigated in two noncommon metals: YBa2Cu3Ox, high-T-c mater ial doped with 1% Gd, and Rb1C60, linear polymer phase fulleride. In the fi rst case, the Korringa-like temperature dependence of the Gd3+ longitudinal relaxation time T-1 is found for x = 6.59 in a wide temperature range 4.2 < T < 200 K, both above and below T-c = 56 K. At x = 6.95 (T-c = 90 K), the T-1 behavior within 50 < T < 200 K is evidently affected by spin gap openi ng with the gap value of about 240 K. At 200 K, an unexpected acceleration of the relaxation rate takes place, suggesting some change in the relaxatio n mechanism. The data are discussed in terms of the Barnes-Plefke theory wi th allowance made for microscopic separation of the normal and superconduct ing phases. In Rb1C60, the evolution of the ESR line and relaxation rates h ave been studied accurately in the range of the metal-insulator transition (below 50 K). Interpretation is suggested which takes into account breaking down the relaxation bottleneck due to opening of the energy gap near the F ermi surface. The gap value of about 100 cm(-1) is estimated from the analy sis of relaxation rates, lineshape and spin susceptibilities.