EVIDENCE FROM DE HAAS-VAN ALPHEN EFFECT

The amplitude of the de Haas-van Alphen effect is reduced by collision broadening of the Landau levels approximately as if the temperature were raised by an amount x (the Dingle temperature) which is inversely related to an appropriate relaxation time τ. Following a discussion of what is involved in obtaining significant estimates of τ from experimental measurements of x, the rather meagre available results are reviewed. For fairly pure samples, values of x are often found which are as much as 50 times what would be expected from the resistive relaxation time; the evidence suggests that such high values of x are due to small-angle scattering by imperfections, though they may also be due partly to phase smearing effects not connected with collision broadening. The most significant results come from studies of the increases of x due to controlled additions of small amount of impurity. These increases are generally of much the same order of magnitude as would be expected from the increase or residual resistance, though detailed correlation with resistivity is hardly possible where the x measurements refer to a small part of a complicated Fermi surface. Recent results on impurities in the noble metals are beginning to give some indication of the anisotropy of scattering and because of the relative simplicity of the Fermi surface, a more detailed correlation with resistivity is possible. Particularly interesting anomalous behaviour is obtained for transition metal impurities which give rise to the Kondo effect. The possibility of studying phonon scattering through its effect on x is briefly discussed. © 1969 Springer-Verlag.