▎ 摘　　要

Interaction of massless electrons with the acoustic phonons is studied in two-dimensional (2D) graphene at low temperatures by calculating phonon drag thermopower S-g and hot-electron energy-loss rate F(T). S-g and F(T) are studied as a function of temperature T and electron concentration n(s). For very low temperatures S-g similar to T-3 and F(T)similar to T-4 in contrast to S-g similar to T-4 and F(T)similar to T-5 of unscreened deformation-potential coupling in usual 2D systems. We find that S-g is related to the phonon limited mobility mu(p) by S-g mu(p)=v(s)Lambda T-1 (v(s) is the phonon velocity and Lambda is the phonon mean-free path) validating Herring's law for linear dispersion of electrons in graphene. In the low-temperature limit S-g, F(T)similar to n(s)(-1/2). For comparison diffusion thermopower S-d is calculated and S-d similar to T, n(s)(-1/2). Our results are compared with those in the usual 2D systems.