Sk. Misra, Spin-lattice relaxation times in amorphous materials as effected by exchange interactions, tunneling level states (TLS) centres, and fractons, SPECT ACT A, 54(14), 1998, pp. 2257-2267
Citations number
44
Categorie Soggetti
Spectroscopy /Instrumentation/Analytical Sciences
Journal title
SPECTROCHIMICA ACTA PART A-MOLECULAR AND BIOMOLECULAR SPECTROSCOPY
The processes of spin-lattice relaxation (SLR) in amorphous materials are r
eviewed. In particular, the mechanisms involving exchange interaction, tunn
eling level states (TLS) centers and fractons predominant in effecting elec
tron SLR at low temperatures in amorphous materials are reviewed. It has be
en deducded that the former two lead to quadratic temperature dependences a
t very low temperatures and linear temperature dependences at intermediate
temperatures of the relaxation rate in amorphous materials. As for relaxati
on due to fractons in fractal state, the theories proposed by Alexander, En
tin-Wohlman and Orbach (Phys. Rev. B 32 (1985) 6447; Phys. Rev. B 33 (1986)
3935; J. Phys. Lett. 46 (1985) 1555) are reviewed and the temperature depe
ndences of fracton-assisted relaxation rate in the fractal state for Kramer
s and non-Kramers ions are examined. (C) 1998 Elsevier Science B.V. All rig
hts reserved.