Investigations into the tunneling magnetoresistance effects in thin films of (La1−yPry)1−xCaxMnO3

Abstract

Thin lms of (La1−yPry)1−xCaxMnO3 (LPCMO) are known to undergo phase separation between a ferromagnetic metallic (FMM) phase and a charged-ordered insulator (COI) phase. When cooled down from room temperature to achieve this phase separation, it appears that the FMM regions can move through the COI regions as if they were in a uid, which is known as the uid phase separated (FPS) state. By manipulating the FMM regions in the FPS state using magnetic and electric elds, one can achieve tunneling magnetoresistance (TMR) e ects desirable for the creation of magnetic tunnel junctions (MTJs), which are useful for data storage. In this investigation, two di erent LPCMO samples were fabricated, one with metal contacts separated by a few millimeters (the \millimeter" sample) and another with contacts separated by a few micrometers (the \micrometer" sample). It was observed that TMR e ects were present in the \micrometer" sample, but not in the \millimeter" sample, indicating that the \micrometer" sample is more useful than the \millimeter" sample for the creation of MTJs. In addition, electric eld e ects on TMR were observed, but are not yet fully understood.