LAUSR

Bulk $1T\text{\ensuremath{-}}\mathrm{TiT}{\mathrm{e}}_{2}$ (hexagonal, space group P-$3m1$) exhibits semimetallic conductivity with weak Anderson localization characteristic at ambient pressure, but superconductivity under high pressure of $\ensuremath{\sim}5\phantom{\rule{0.16em}{0ex}}\mathrm{GPa}$. Here the detailed evolutions of structural and transport properties in $\mathrm{TiT}{\mathrm{e}}_{2}$ during compression are investigated by extending pressure up to 50.2 GPa. The combined high-pressure electrical transport and synchrotron x-ray diffraction experiments unravel two critical pressure points. At ${P}_{c1}\ensuremath{\sim}5.4\phantom{\rule{0.16em}{0ex}}\mathrm{GPa}$, the superconductivity emerges, which is accompanied by a structural transition from $P\text{\ensuremath{-}}3m1$ to a mixture of $P\text{\ensuremath{-}}3m1$ and monoclinic $C2/m$ phase. The localization effect maintains until the structural transition is over at ${P}_{c2}\ensuremath{\sim}19.1\phantom{\rule{0.16em}{0ex}}\mathrm{GPa}$, meanwhile the Hall coefficient ${R}_{\mathrm{H}}$ changes from positive to negative. Our results demonstrate that the superconductivity in the pressurized $\mathrm{TiT}{\mathrm{e}}_{2}$ can be assigned to the high-pressure $C2/m$ phase which is electron dominated.