NMR RELAXATION STUDIES OF ELECTRONIC-STRUCTURE IN NBSE3

NMR spin-lattice relaxation measurements of the Nb-93 resonance for each Nb site were performed on an aligned, multicrystalline NbSe3 sample at different temperatures. Results are associated with local electron densities of states for each of the three crystallographic sites, demonstrating Fermi-surface changes associated with the two charge-density-wave phase transitions. The most significant Fermi-surface changes occur for the yellow and orange crystallographic sites, at the high- and low-temperature phase transitions, respectively. The third site, however, is found to be noninsulating. A comparison is made to band theory and other experimental results.