Magnetoconductivity of insulating silicon inversion layers

The normalized in-plane magnetoconductivity of the dilute strongly interacting system of electrons in silicon metal--oxide--semiconductor field effect transistors scales with $B∕T$ for low densities in the insulating phase. Pronounced deviations occur at higher metalliclike densities, where an energy scale kBΔ emerges which is not associated with either magnetic field or thermal effects. While the energy scale kBΔ vanishes at n₀ approaching from the metallic side, we do not find a finite Δ which goes to zero approaching n₀ from the insulating side.