Low-temperature magnetoconductance transition to Mottșs conductance

The conductivity of an amorphous sample at low temperatures in a strong magnetic field is calculated. While Mottșs and Ono"s theories consider infinite samples, the proposed formalism treats finite ones. It turns out that this is a crucial difference. The model shows a transition between two conductivity behaviors: ln (σ)≈(Formula presented) for T<T-tilde and ln (σ)≈-(Formula presented) for T>T-tilde (the transition temperature T-tilde depends on the magnetic field and on the sampleșs size). The former one resembles the simple two-dimensional Mott conductivity behavior, while the latter resembles Ono"s theory.