Abstract
Among the perovskite oxides, Mixed valence manganites LaxA1-xMnO3 (A is divalent ions such as Ca2+, Sr2+ or tetravalent ions like Sn4+, Zr4+) has been studied for its noticeable electrical, magnetic and magnetoresistive properties. Perovskite LaxHf1-xMnO3 (LHMO) is a tetravalent cation doped manganite in which the La3+ ions of the parent compound LaMnO3 are substituted by tetra-valence Hf. In comparing with other tetravalent elements, hafnium has an ion radius close to that of trivalent lanthanum and show a sole trtravalent state. These make the study on the valence structure of LHMO system relatively simple and more reliable. The LHMO is also susceptible to a branch of stimuli, e.g. electric fields/currents, lights, strain and pressure.
I will firstly give some brief introductions on the structure of the perovskite oxides, the Jahn-Teller Effect and double exchange theory. Then some literature reviews about the field modulation on transport properties in LaxA1-xMnO3 will be illustrated. The ER effect, the photo illumination modulation and lattice strain modulation will be mainly focused on. Lastly, some details of my research proposal will be given.