New features of the Shubnikov–de Haas effect in bismuth

Simultaneous measurement of both the nondiagonal and diagonal components of the magnetoresistivity tensor in a magnetic field transverse to the current density vector j (made without the conventional use of filters and angle modulation) has revealed the possibility of observing, near the trigonal axis of bismuth, Shubnikov–de Haas oscillations associated with only the electron part (according to the ρyx data) or only the hole part (according to the ρxx data) of its Fermi surface. With the magnetic field vector H in the same or nearly the same direction, there occurs at temperatures T < 4.2°K a shift of the ρyx extrema which is due to changes in the temperature. The oscillation period remains constant, moreover, and the magnitude of the thermal phase shift does not depend on the magnetic field intensity. For the first time here the amplitude of magnetoresistivity oscillations in a transverse field was found to increase as a result of temperature changes, namely: With the direction of vector H close to that of the trigonal axis, the amplitude of oscillations ρ˜yx was found to vary nonmonotonically with the temperature, with the derivative ∂ρ˜yx/∂T reversing sign twice within the 1.7−7.6°K range. These unusual properties of Shubnikov–de Haas oscillations in the j⊥H configuration are manifested in a superposition of two effects: blurring of the density of electron states and enlargement of the effective cross section for electron scattering by phonons with increasing temperature. In principle, the possibility of wider oscillations of the transverse magnetoresistivity with increasing temperature is demonstrated for the case kT≲ (2 mHħΩc)1/2s.