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 X is highly anisotropic in k(parallel to). For a three-dimensional band close to (Gamma) over bar we find lambda = 0.54 +/- 0.03 while the e-p coupling with electrons from a nearby two-dimensional band is only lambda = 0.05 +/- 0.01. Another two-dimensional highly dispersive and very narrow band with a Fermi momentum of only k(F) = 0.0084 angstrom(-1) close to (M) over bar 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 E-i = -24 meV is only lambda =0.007 +/- 0.005 and does not seem to further increase for holes closer to the Fermi level. (c) 2005 Elsevier B.V. All rights reserved.