Observation of a size effect in laser-induced thermomagnetic potentials in bismuth thin films

Classical size behavior of the Nernst-Ettingshausen effect induced by pulsed laser light in bismuth films

“…5 This observation, together with that of Ref. 1, reveals the important influence of the surface on the laser-induced transport phenomena.…”

“…The thermomagnetic coefficient in the 0.15-m and 5.5-m films is positive and increases as the magnetic field increases, as already observed. 1,2 In the 0.19-m film, the thermomagnetic signal consists of a negative pulse followed by a positive pulse, the first peak decreasing and the second peak increasing as the applied magnetic field increases. Readings of each peak were taken and different values of the thermomagnetic coefficient were assigned to each one.…”

“…The Nernst-Ettingshausen ͑NE͒ effect showed a classical size effect that affected the sign of the induced potential and its dependence on film thickness and temperature. 1 A later study included the measurement of the laser-induced NE effect in films as thick as 5.5 m, where size effects were not expected to appear. This study resulted in a monotonically increasing positive NE coefficient versus the magnetic field, behavior that cannot be explained if only one type of carrier is considered in the resolution of the Boltzmann equation.…”