Proton spin-lattice relaxation mechanisms and the metal-insulator transition in cerium hydrides

• Published in: Physical review. B, Condensed matter Condensed matter, 1984, Vol.29 (1), p.61-70
• Main Authors: ZAMIR, D, BARNES, R. G, SALIBI, N, COTTS, R. M, PHUA, T.-T, TORGESON, D. R, PETERSON, D. T
• Format: Article
• Language: English
• Subjects: Condensed matter: electronic structure, electrical, magnetic, and optical properties; Exact sciences and technology; Magnetic resonances and relaxations in condensed matter, mössbauer effect; Nuclear magnetic resonance and relaxation; Physics; Relaxation effects
• ISSN: 0163-1829; 1095-3795
• DOI: 10.1103/physrevb.29.61

Nuclear-magnetic-resonance (NMR) experiments have been done on cerium hydride (CeH sub x ) samples to search for correlations between NMR properties and known electrical conductivity changes as a function of hydrogen concentration and temp. Data are presented for the exp 1 H spin-lattice relaxation rate R sub 1 ( = 1/T sub 1 ) and some line shapes for 2.10 < = x < = 2.92 for temp. from approx 100 to 375K. Proton spin-lattice relaxation is characterized by a single relaxation time at each x and T . The marked decreases in R sub 1 and in the electrical conductivity that are associated with the concentration-dependent transition are thus attributed to the vanishing electron density-of-states at the Fermi surface. No temp.-dependent transition in R sub 1 is found. Results are consistent with a Mott transition model in which the electron donors are H vacancies. 28 ref.--AA