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The dependence of the magnetic freeze-out and the sign change of the Hall effect on impurity concentration, compensation and temperature has been investigated under uniaxial stress up to 4 kbar in the magnetic field range of 1–10 Tesla. Both the transverse and longitudinal conductivity are strongly increased by an uniaxial stress of some kbar. While the zero-stress results were described by a quantum transport theory including the effect of the nonparabolicity of the conduction band on ionized impurity scattering consistently, this theory fails to reproduce the stress dependence of the conductivity tensor.

Nuclear transmutations by thermal neutrons are used to control the doping characteristics of n-InSb in a systematic way. The concentration of the produced donors is determined by an analysis of Hall effect and mobility measurements in a temperature range where ionized impurity scattering dominates. This concentration agrees very well with the additional donor concentrations calculated from the total flux of the thermal neutrons. Durch Kernumwandlung mittels thermischer Neutronen konnte die Dotierung von n-InSb systematisch variiert werden. Die Konzentration der erzeugten Donatoren wurde durch eine Analyse von Halleffekt- und Beweglichkeitsmessungen in einem Temperaturbereich bestimmt, in dem Streuung an ionisierten Storstellen dominiert. Mit Werten, die aus dem totalen Flus der thermischen Neutronen bestimmt wurden, konnte sehr gute Ubereinstimmung erzielt werden.

At liquid helium temperatures a change of the sign of the Hall effect of n-InSb is observed in the magnetic freeze-out regime. The experimental examination of possible explanations and their discussion show that only the contribution of the asymmetric impurity scattering (“skew scattering”) to the Hall effect explains the observed systematic behaviour of the sign change. Bei Temperaturen des flussigen Heliums beobachtet man in n-InSb im Bereich des magnetischen Ausfrierens einen Vorzeichenwechsel des Halleffekts. Die experimentelle Uberprufung verschiedener Erklarungsmoglichkeiten und deren Diskussion zeigt, das nur der Beitrag der asymmetrischen Fremdionenstreuung (“skew scattering”) zum Halleffekt die experimentell beobachtete Systematik des Vorzeichenwechsels erklaren kann.

Recently, contradicting results concerning magnetotransport experiments on n-InSb at liquid helium temperatures have been reported by various authors. The authors' experiments show that the assumption of the existence of a conducting surface layer due to soldering of tin contacts to the samples is not valid. Experiments on samples treated by careful etching procedures have proven the sign change of the Hall effect and the saturation of the transverse magnetoresistance to be bulk effects.

A stress apparatus is reported which allows us to apply forces up to 300 N to solids perpendicular to the field in a superconducting magnet. This configuration is necessary to study stress dependences of transverse magneto‐transport effects and magneto‐optical properties in Faraday geometry. The usefulness of the apparatus is demonstrated by Hall effect and transverse magnetoresistance measurements in n‐InSb as well as far‐infrared cyclotron resonance experiments on n‐Ge.

A change of the sign of the Hall coefficient is observed in n-InSb with carrier concentrations from 5 x 1013 to 1015 cm−3 at liquid helium temperatures and magnetic fields above some 20 kG. The influence of doping is investigated systematically. The sign change is discussed in the light of the anomalous Hall effect due to spin-orbit interaction.