Magneto-seebeck effect in graphite: Giant thermoelectric power due to phonon drag

The in-plane thermoelectric power () of single-crystal graphite in the presence of a magnetic field applied parallel to the c direction was measured at temperatures (T) from 4.2°K up to 300°K. With an increase of the field intensity (H), the sharp negative dip of the  versus T diagram previously found to be (0) = −11.5μv/°K at 35°K exhibited a slight shift of position to near 30°K and a remarkable growth of depth to (H) ⋍ −80μv/°K for H = 1.7 kG and (H) ⋍ − 2000 μv/°K for H = 8.0 kG. In accordance with Sugihara's theory on the phonon drag effect in semimetals, these anomalies have been ascribed to the strong interaction between carriers and phonons in graphite.