Distinctive features of the magnetoresistance of degenerately doped n-InAs and their influence on magnetic-field-dependent microwave absorption

Magnetic-field-dependent microwave absorption and electron spin resonance are used to investigate magnetoresistive effects in strongly doped n-InAs. It is shown that these effects can be traced back to negative, positive, or oscillatory magnetoresistance (i.e., the Shubnikov-de Haas effect). While the experimental data are in agreement with the predictions of theory in the latter two cases, for the negative magnetoresistance there are features that are difficult to interpret, especially the absence of any effect at very small fields, much smaller than the characteristic field Hϕ that appears in the theory of quantum corrections, and the two-dimensionality of bulk samples in fields much larger than Hϕ implied by the observed dependences on temperature and to some extent on the magnetic field.