High-pressure studies on the properties of FeGa3 : Role of on-site Coulomb correlation

High-pressure x-ray diffraction measurements have been carried out on the intermetallic semiconductor ${\mathrm{FeGa}}₃$ and the equation of state for ${\mathrm{FeGa}}₃$ has been determined. First-principles based DFT calculations within the GGA approximation indicate that although the unit cell volume matches well with the experimentally obtained value at ambient pressure, it is significantly underestimated at high pressures and the difference between them increases as pressure increases. $\mathrm{GGA}+U$ calculations with increasing values of ${U}_{\mathrm{Fe}(3d)}$ (on-site Coulomb repulsion between the Fe $3d$ electrons) at high pressures, correct this discrepancy. Further, the $\mathrm{GGA}+U$ calculations also show that along with ${U}_{\mathrm{Fe}(3d)}$, the Fe $3d$ bandwidth also increases with pressure and around a pressure of 4 GPa, a small density of states appear at the Fermi level. High-pressure resistance measurements carried out on ${\mathrm{FeGa}}₃$ also clearly show a signature of an electronic transition. Beyond the pressure of 19.7 GPa, the diffraction peaks reduce in intensity and are not observable beyond $\ensuremath{\sim}26\phantom{\rule{4pt}{0ex}}\mathrm{GPa}$, leading to an amorphous state.