Hall measurements of the insulating phases at υ = 1.5 and υ ∼ 0.5 in p-type Si/Si_1-xGe_x heterostructures using pulsed magnetic fields

Abstract

Low temperature (0.3 K) Hall resistivities (ρxy) of the two dimensional hole system in high quality p-type Si/Si1-xGex single heterojunctions have been measured in pulsed magnetic fields to 50 T. Clean Hall measurements are obtained by subtracting the raw signals from four separate field pulses. Hall data are presented in the Landau level filling factor regime υ = 1.5 where we have previously identified an insulating phase (IP). This IP, characterised by a rapid increase in ρxx as T → 0 K and non-linear I-V measurements, is shown to increase at large tilt angles. The corresponding Hall resistivity in the IP region, measured in tilted pulsed magnetic fields, remains finite and close to the classical value. Preliminary pulsed magneto-transport results are presented for a second IP which indicate that both ρxx and ρxy increase dramatically for υ < 0.5. © 1998 Elsevier Science B.V. All rights reserved.