Appearance of semiconductor-to-metal transition in Ba 2 BiFeSe 5 single crystal: A combined DFT and transport analysis under pressure

We investigate chalcogenide Ba 2 BiFeSe 5 compound under pressure, focusing on temperature-dependent electrical resistivity ρ ( T ) upto 16.5 GPa and density functional theory ( DFT ) calculations up to 25 GPa. We assess Activation energies ( Ea ) and Bandgap calculations via the density of states ( DOS ). Our experimental results indicate a pressure-induced semiconductor-to-metal transition (STM) occurring at 14.3 GPa and transition is evident through the decreasing resistivity values from 14.7 × 10 5 Ω-cm to 0.00022 × 10 5 Ω-cm at 100 K and the calculated Ea, which decreases from 0.168 to 0.029 eV within 0–12 GPa range, followed by a sudden drop to 0.0007 eV at 14.3 GPa, signifying pressure-induced STM transition. Meanwhile, our DFT calculations reveal minor changes in the electronic band structure around 14 GPa. Furthermore, high-pressure DFT structural investigations affirm the stability of the Ba 2 BiFeSe 5 system in a metallic state up to approximately 25 GPa. This unique phase transition holds significant promise for inspiring a diverse array of potential applications. Graphical abstract