Universality at a quantum Hall – Hall insulator transition in a Si/Si0.87Ge0.13 2D hole system

The temperature dependence of the magnetoresistivity of a Si/Si0.87Ge0.13 2D hole system with View the MathML source and View the MathML source (at 50 mK) has been studied. An insulating phase is observed for ν<1, with ρxy remaining finite and close to h/e2, indicating a possible quantised Hall insulator state. The data on either side of the ν=1 to Hall insulator transition can be scaled to a single pair of curves with a scaling exponent of κ=0.68±0.05. Temperature-independent conductivities close to ν=0.69 and ν=1.5 are found to appear at values of View the MathML source and View the MathML source, respectively, in agreement with theory.