Pressure-induced disruption of the local environment of Fe-Fe dimers in FeGa3 accompanied by metallization

The semiconducting gap in the FeGa3 intermetallic originates from Fe(3d)/Ga(4p) hybridization. Pressures of 15-20 GPa initiate a disruption of this semiconducting tetragonal P42/mnm structure and an emergence of a high-pressure metallic phase, estimated to be fully stabilized just beyond ∼35 GPa. An accompanying pronounced ∼17% volume collapse occurs at the structural transition. The high-pressure metallic phase has a T1/2 temperature dependence of the resistivity below its minimum at 8-12 K, symptomatic of disorder. There is a corresponding weak high-temperature dependence of the resistivity and resultant broad maximum at ∼250 K to yield "bad-metal" values of ∼0.5 mΩ cm at room temperature. This is shown to signify that the high-pressure phase is a low carrier density metal on the verge of an Anderson transition. Ga K-edge absorption spectroscopy and Fe Mössbauer spectroscopy local probes indicate that the atomic disorder stems from a pressure-instigated rearrangement of the Ga sublattice at the structural transition.