Pressure-induced metallization of the Mott insulator FeXMn1-XS system

Electrical resistivity of the Fe_XMn_1−XS (0 ≤ X ≤ 0.29) single crystals based on the Mott insulator α-MnS is experimentally studied in the temperature range of 2–300 K at ambient pressure (P = 0) and at high (up to 30 GPa) hydrostatic pressures for x = 0.12. The electron subsystem of Fe_XMn_1−XS undergoes insulator-to-metal transitions indicated by a resistivity drop by a factor of 10⁶ with an increase in the chemical pressure (X) due to the cation substitution under ambient conditions and at the hydrostatic pressure (P_C = 27 ± 5 GPa) for x = 0.12. The results obtained show that the hydrostatic pressure - and cation-substitution induced insulator-to-metal transitions in the α-MnS-based Mott compounds have similar mechanisms. The dependence of the critical hydrostatic pressure P_C on the Fe content in Fe_XMn_1−XS is established.