Density of states effective mass of n-type CuInSe2 from the temperature dependence of Hall coefficient in the activation regime

The Hall coefficient RH of n-type CuInSe2 single crystals is measured between 10 and 300 K in pulsed magnetic field up to 35 T. The threshold field Bth, above which the magnetic freezeout starts to occur, varies linearly with temperature. From the analysis of the temperature dependence of electron concentration in the activation regime above 100 K at different field values, it is established that the density of states effective mass me∗=(0.090±0.001)me is independent of the magnetic field B and the activation energy ED, above around 6 T, varies as B1/3. Similar B1/3 dependence of the magnetoresistance in the high magnetic field regime, reported earlier in the same material, suggests that theoretical work that could explain this coincidence is needed.