Resistivity of two-dimensional systems in a magnetic field at the filling factor ν = 1/2

Experimental data on the diagonal resistivity ρ _xx of GaAs/AlGaAs heterostructures in a magnetic field at the filling factor ν = 1/2 have been compared with the existing theoretical predictions [B. I. Halperin et al., Phys. Rev. B 47, 7312 (1993) and F. Evers et al., Phys. Rev. B 60, 8951 (1999)]. The experimental results have been found to follow the relation ρ _xx (1/2) ∝ n ⁻² d ^−1.64, which disagrees with the predictions.