Evidence for Bloch-Gruneisen Behavior in the 1:2:4 Phase Measured in an Extended Temperature Range

The resistivity rho(T) of the 1:2:4 phase YBa sub 2 Cu sub 4 O sub x, when measured between T sub c=80K and T=300K, has been found to exhibit a seemingly anomalous negative intercept rho(0) 0. We measured rho(T) in a pure-phase film of 1:2:4 from 60K (in a magnetic field) to 600K and obtained a temperature dependence resembling Bloch-Gruneisen behavior with rho(T) in 1:2:3 and the nonlinear rho(T) in 1:2:4 can be related to the larger carrier concentration in the latter : we speculate that 1:2:3 has smaller Fermi surface and hence smaller effective transport Debye temperature than 1:2:4.