QUANTUM CORRECTIONS TO THE CONDUCTIVITY IN MAGNETIC-FIELD AND NEGATIVE MAGNETORESISTANCE OF ZINC SELENIDE

An analysis of the negative magnetoresistance (NMR) of n-ZnSe crystals is made for the first time in frames of a new theory of this phenomenon based on quantum corrections for the conductivity in a magnetic field. The study is carried out for a wide concentration range (2.5 x 10(16) to 7.4 x 10(17) cm-3) at low temperature (1.65 to 4.2 K). In samples with metallic conductivity the NMR is shown to be well described by means of a localization quantum correction only for weak magnetic fields. With increasing strength of the magnetic field the contribution of anomalous positive magnetoresistance also increases, being related to the quantum correction, which arises from the state density decrease due to electron-electron interaction. The NMR is detected in heavily doped compensated (HDC) samples with low-temperature conductivity of the Mott type, caused by the state density increase near the Fermi level in the magnetic field.