Pressure-induced electronic and magnetic phase transitions in a Mott insulator: Ti-dopedCa3Ru2O7bilayer ruthenate

Abstract

We report the hydrostatic pressure-induced electronic and magnetic phase transitions in a Mott insulator, a bilayer ruthenate $\mathrm{C}{\mathrm{a}}_{3}{(\mathrm{R}{\mathrm{u}}_{0.97}\mathrm{T}{\mathrm{i}}_{0.03})}_{2}{\mathrm{O}}_{7}$, via electronic transport and single crystal neutron diffraction measurements. The system undergoes an insulator-metal transition at a very small hydrostatic pressure \ensuremath{\approx}0.04 GPa, followed by a magnetic phase transition around 0.3 GPa, suggesting that the low energy charge fluctuation and magnetic ordering couple to the pressure separately in this compound. The $ab$ initio calculations show that the suppressed $\mathrm{Ru}{\mathrm{O}}_{6}$ flattening induced by the pressure reduces the orbital polarization and gives rise to an insulator-metal transition preceding the magnetic phase transition.