Lack of electron-phonon coupling along two-dimensional bands in Bi1−xSbx single crystal alloys

From the temperature dependent broadening of high-resolution angle resolved valence band spectra of Bi0.92Sb0.08, we deduce the electron-phonon (e-p) interaction in several bands close to the Fermi level. Our data indicate that the e-p coupling constant λ is highly anisotropic in k∥. For a three-dimensional band close to Γ¯ we find λ = 0.54 ± 0.03 while the e-p coupling with electrons from a nearby two-dimensional band is only λ = 0.05 ± 0.01. Another two-dimensional highly dispersive and very narrow band with a Fermi momentum of only kF = 0.0084 Å−1 close to M¯ in the direction perpendicular to the bisectrix-line is nearly temperature independent. The e-p coupling constant for holes at the bottom of this band at Ei = −24 meV is only λ =0.007 ± 0.005 and does not seem to further increase for holes closer to the Fermi level.