Magnetoresistance in the strongly insulating regime of GaAs two-dimensional hole systems

Magnetoresistance (MR) of GaAs two-dimensional hole systems (2DHSs) is investigated in the strongly insulating regime. By rotating the samples, the total magnetic field B-tot and the perpendicular component B-perpendicular to to the 2DHS are controlled independently. In the low-B-perpendicular to region, a large positive B-perpendicular to-dependence of the longitudinal resistivity rho(xx) is observed when B-tot is small, while it is replaced by a negative one when B-tot is large. For higher B-perpendicular to, dips are observed in the rho(xx) vs B-perpendicular to curve and the values of B-perpendicular to at the dip depend on B-tot. The results are discussed both in the framework of single-particle localization and in the framework of Wigner crystallization. (c) 2006 Elsevier B.V. All rights reserved.