Longitudinal galvanomagnetic effect in thin bismuth films
Annotatsiya
The longitudinal magnetoresistance of epitaxial Bi films with a thickness of 1300–4000 Å is investigated at 4.2 °K. In a perpendicular magnetic field, these specimens clearly show magnetic quantization (Shubnikov–de Haas effect). The dependence of the longitudinal magnetoresistance on the magnitude of the magnetic field shows a maximum that has a quantum nature (transition to the quantum limit with respect to the magnetic field). With the help of a modulation technique, in recording the derivative ∂R/∂H(H), it was possible to reveal the Shubnikov–de Haas oscillations, related to the manifestation of magnetic quantization in one of the electronic valleys [period of oscillations is Δ(H−1) ≃ 2.25 · 10−5 Oe−1]. Together with this, in recording the second derivative ∂2R/∂H2(H), for small magnetic fields, it was possible to observe features that in our opinion are related to the appearance of a classical galvanomagnetic size effect in the longitudinal magnetic field. The mean free path of charge carriers in the bismuth films investigated was measured from the position of these features on the magnetic field axis.