Strain influence on the diffusion thermopower in Bi wires

Abstract

We present the results of studies of the thermopower in glass-coated Bi wires under the action of uniaxial deformation. At the liquid helium temperature, thin Bi wires exhibit large positive thermopower values, which are dominated by the diffusive transport mechanism of holes. The observed increase in the negative contribution to total thermopower under uniaxial strain testifies that the hole-dominated transport can be transformed into the electron-dominated transport. The observed trend to negative thermopower values under strain can be attributed partially to a slight increase in the electron mobility and partially to the occurrence of the phonon drag effect of electrons. The phonon drag effect prevails in the thermopower, if the phonons acquire a sufficient momentum to scatter the carriers across the Fermi surface changed after an Electronic Topological Transition.