| Summary: | 碩士 === 國立中山大學 === 物理學系研究所 === 92 === 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.
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