Enhancement of electronic transport and magnetoresistance of

We have used a non-magnetic ${\rm Al}_{2}{\rm O}_{3}$ barrier, impregnated in $({\rm La}_{0.5}{\rm Pr}_{0.2}){\rm Sr}_{0.3}{\rm MnO}_{3}$ (LPSMO) thin film layers, to obtain large magnetoresistance (MR) in the vicinity of room temperature. In the magnetic field of 1T, the LPSMO/${\rm Al}_{2}{\rm O}_{3}$/LPSMO heterostructure exhibits an MR of $\sim 35{\%}$ at its insulator-to-metal transition temperature ($T_{{\rm IM}}$) of $\sim 220\,{\rm K}$ vis-à-vis an MR of $\sim 8{\%}$ in the pristine LPSMO film at its $T_{{\rm IM}}$ of 298 K. This enhanced MR, coupled with a 2- to 3-fold increase in the temperature coefficient of resistance and the field coefficient of resistance in the heterostructure compared to that in the LPSMO films, demonstrates the efficiency of this technique in engineering those physical properties of manganites which have potential bearing on the realization of their technological applications