Geometric contribution to the measurement of thermoelectric power and Nernst coefficient in a strong magnetic field

On the measurement of thermoelectric power and Nernst coefficient, we used two kinds of shapes for a sample. One is "Bridge shape" and the other is, we call,"Fat-Bridge shape". The latter has 5 times wider main body than the former. We used pure n-InSb in this experiment, whose carrier condensation measured at 77K was $6.6 \times 10^{-14} cm^{-3}.$ The length of sample is 17mm and temperature difference induced between the edges in that direction were about $10^{\circ}$C or $100^{\circ}$C near a room temperature range of 0 to $100^{\circ}$C. Magnetic induction applied in the perpendicular direction to temperature gradient was in the range of 0 up to 4 Tesla. In the case of "Fat-Bridge shape", we detected about 10% smaller Nernst coefficient and 1 to 10% smaller thermoelectric power comparing to the "Bridge shape". We suppose this phenomena is due to the geometric contribution on the different shape of samples.