Formation of the sodium 1-D structures in doped NaCl by high energy electron irradiation

An investigation of the formation and properties of linear sodium structures in electron-irradiated potassium doped NaCl crystals was carried out by means of electron spin resonance (ESR) and nuclear magnetic resonance (NMR). It has been found that the behavior of ESR and NMR signals depends on the dose and temperature. The most interesting properties were observed in heavily irradiated samples. The magnetic spin susceptibility determined by ESR signal intensity showed temperature insensitive Pauli paramagnetism at high temperature and then decreased below 160 K, indicating metal-insulator transition (MIT). The nuclear spin-lattice relaxation rate T1^-1 showed a remarkable (root) frequency dependence, which is due to the one-dimensional diffusive motion of electrons. The influence of some impurities on the formation of microstructures has been studied too and the nature of the MIT at low temperatures in heavily irradiated NaCl:K crystals is discussed.