Browsing Brock Theses by Author "Jacob, Sarkis Y."
Systematic studies of the effect of pressure on magnetic and electronic properties of La2/3Ca1/3MnO3 thin films with various thicknesses /Jacob, Sarkis Y.; Department of Physics (Brock University, 1999-05-21)Interest in mixed-valent perovskite manganese oxides of La\-xAxMnO^ (v4-divalent alkaline earth Ca, Sr or Ba), whose unusual properties were discovered nearly a half century ago, has recently been revived. The discovery of the colossal magnetoresistance and pressure effects introduced new questions concerning the complex interplay between lattice structure, magnetism and transport in doped perovskite manganites. In this study, we report our experimental investigations of pressure and magnetic field dependencies of La-i/sCai/sMnOs (LCMO) epitaxial films with various thickness on SrTiO$ substrate. An analysis of film thickness dependency of the resistivity of LCMO epitaxial films under pressure and magnetic field has been performed by taking into account substrate contributions. This verifies the correlation of lattice distortion with magnetic and transport properties. Strong dependencies of Mn — O — Mn bond bending and Mn — O bond stretching with pressure as well as Mn spin alignment with magnetic field, and the lattice distortion induced by the substrate are discussed.