Evidence of strong spin fluctuations in Si:P close to the metal- insulator transition.
01 January 1985
The spin-lattice relaxation time T1 of (29)Si nuclei is measured at the metal-insulator transition as a function of temperature and magnetic field. The observed relaxation rate in the metal is up to 10(3) times larger than that for nuclei interacting with free, degenerate electrons. The enhanced relaxation rate and its magnetic field dependence suggest the existence of strong spin fluctuations with an omega(-1) power spectrum. These slow, nearly localized spin fluctuations can cause spin flip scattering and may be responsible for the anomalous critical exponent of the electrical conductivity.