HALL-EFFECT AND MAGNETORESISTANCE IN SRXNBO3 (X = 0.80, 0.85, AND 0.90)

Both the Hall coefficient and the magnetoresistance have been measured for polycrystalline samples of SrxNbO3 (x = 0.80, 0.85, and 0.90). The Hall coefficient is found to be negative and weakly dependent on temperature for every sample. The carrier concentration (n) is comparable with that for a conventional metallic conductor, i.e., n approximately 10(22) cm-3 at 5 K. The effective mass (m*) is estimated to be m* approximately 3m0 using the free-electron model (where m0 is the free-electron mass). The metallic parameter k(F)l(tr) (in which k(F) is the Fermi wave number and l(tr) is the transport mean free path) is rather small being approximately unity, though the typical value for a metal is k(F)l(tr) much greater than 1. The increase in magnetoresistance (DELTArho/rho) at H = 6 T, DELTArho/rho = {rho(H) - rho(0)}/rho(0), is estimated at 1.5-3 %. As H increases, DELTArho/rho increases in proportion to H-2 up to H approximately 3 T, and then linearly with H. In order to explain this result we discuss the transport property of SrxNbO3 in terms of quantum-interference phenomena such as weak localization or electron-electron interaction effects.