On the role of the correlation length near the onset of non-metallic conduction

The conductivity of indium oxide films was studied as a function of k _Fl (including k_Fl<or approximately=1), film thickness, temperature and magnetic field. For sufficiently thin films the authors observe a change from logarithmic to faster temperature dependence below a temperature determined by R_{Square Operator}. The analogous crossover for thicker samples is shown to depend on k_Fl. Whether a given system is 'thin' enough for R_{Square Operator} to be the relevant parameter in this respect is determined by the value of the correlation length xi .