Hole-doped colossal magnetoresistance (CMR) materials La1-xAxMnO3 (A=alkaline metal, 0≤x≤1) has been extensively studied because of its colossal magnetoresistance (CMR) characteristic in a magnetic field. Recently, many suspicious electron-doped CMR materials have been reported. However, none of these ¡§pure phases¡¨ were supported directly by experiment evidences, instead, various impurity phases were found. The La0.7Ce0.3MnO3 (LCeMO) target forming by a solid state reaction method, after analyzing its crystal structure and electric transport properties, is also found to be decomposed into CeO2 impurity and a La deficient La1-dMnO3 phases. This is believed to because the doped Ce4+ ions transforming the Mn3+ ions to Mn2+ whose larger ionic radius (aMn2+ =0.83Å), comparing to that of Mn3+(0.645Å), makes the MnO6 structure instable. Therefore, instead of forming an instable phase, the sample prefers to decompose into different phases. In this study, we propose to grow LCeMO films on an in-plane-enlarged STO bottom layer which was grown under a tensile strain on MgO (c=4.216Å) substrate. We found that all as grown films exhibits insulating behavior. Nevertheless, the samples after a rapid thermal annealing process can easily decompose the films into multiphase.

Hole-doped manganite La0.7Ca0.3MnO3 materials has been extensively studied because of its colossal magnetoresistance (CMR) characteristic in a magnetic field. Recently, a new member of CMR family La0.7Ce0.3MnO3 , an electron-doped manganite, raises a new wave of attention for possible application of p-n junctions. Single Phase La0.7Ce0.3Mn3 films were usually grown by the pulse laser deposition (PLD) technique with a relatively narrow growth window around 755¢J¡Ó5¢J. In this study, we use a RF sputtering technique to grow La0.7Ce0.3Mn3 epitaxial films, which has not been tried yet. Films are grown on SrTiO3, MgO and LaAlO3 substrates. The best film have the metal-insulator transition temperature (TP) 304K and the curie temperature (TC) 310K, which are higher than that of grown by PLD method

Hole-doped manganite La0.7Ca0.3MnO3 (LCMO) was extensively studied because of its colossal magnetoresistance (CMR) characteristic in a magnetic field. Recently, a new member of CMR family La0.7Ce0.3MnO3 (LCeMO), an electron-doped manganite, raises a new wave of attention for possible application in p-n junction. In this present study, LCMO and LCeMO single layer and bi-layer were grown on SrTiO3 (100) substrate by a pulse laser ablation technique. Due to the neutralization at the p-n junction a possible insulating layer with the anti-ferromagnetic (AFM) property is expected. There is no systematically study of this matter up to date, thus, it is worth to systematically investigate the physical properties of this junction. The result indicates the possible neutralization layer exhibits huge resistance comparison with two lateral layers, the bias current is constrained on the limited thickness of the top layer, which implies the neutralization layer forms a depletion layer that block the current to flow through to the bottom layer. Its electric and magnetic properties may similar to the parent compound LaMnO3 with insulating and anti-ferromagnetic characteristics. Separated by this possible layer, the magnetic coupling between lateral layers is weak. However, the possible AFM layer does pin the magnetic moment of the top layer along the direction perpendicular to the substrate that make a distinct magnetoresistance at low magnetic field.