A local metallic state in globally insulating $L{a}_{1.24}S{r}_{1.76}M{n}_2{O}_7$ well above the metal-insulator transition

Angle-resolved photoemission spectroscopy was used to investigate the evolution of the electronic structure across the metal-insulator transition in bi-layer manganite $L{a}_{1.24}S{r}_{1.76}M{n}_2{O}_7$. We found that this system is a metal for $T<T_C$, a local metal but global insulator for $T<T_C<T^{\ast }$, and a global insulator for $T>T^{\ast }$. These results indicate the critical role of electronic phase separation and percolation effects for the metal-insulator transition in $L{a}_{1.24}S{r}_{1.76}M{n}_2{O}_7$.