POSITIVE MAGNETORESISTANCE IN THE VARIABLE-RANGE-HOPPING REGIME IN COPPER INDIUM DISELENIDE ON EITHER SIDE OF THE CRITICAL-FIELD B-C

Study of the magnetic-field dependence up to 15 T of the positive magnetoresistance is made on n-type CuInSe2 where conduction by the variable-range-hopping mechanism of Mott type is observed below 45 K. It is shown that In[rho(B)/rho(0)] is proportional, at different temperatures up to 40 K, to B-2 and B-1/3 below and above B-c, which separates the weak- and strong-field regimes. This confirms the theoretical prediction for the held dependence of the magnetoresistance when the conduction is by the variable-range-hopping mechanism with constant density of states at the Fermi level.