Tunneling evidence for weak localization in layered manganites*

Our point contact tunneling experiments on La$_{1.28}$Sr$_{1.72}$Mn$_{2}$O$_{7}$ (bi-layered LSMO x=0.36) at low temperatures reveals a $\surd $V low bias anomaly in the tunneling conductance. This anomally qualitatively matches the $\surd $E predictions of the weak localization effect on the electronic DOS. The data could provide an important corroboration of the weak localization hypothesis, which was concluded previously from low-temperature conductivity and magnetoresistance data.