Studies On Electronic And Magnetic Properties Of Artificial Low Dimensional Manganties And Their Manipulation

Perovskite manganites are typical strongly correlated electronic materials. Several novel properties, such as electronic phase separation, colossal magnetoresistance (CMR), etc, has been found in manganites due to the strong correlation interactions between multiple degrees of freedoms. By effective modulating these novel properties would realize the application of manganites in magneto electronics and spintronics, and therefore, the researches on manganites has been the hot spot in the condensed matter physics. In this thesis, we focus on the measurement and modulation of the electronic phase separation properties in manganites. The details are as follows:1. Researches on the spatial modulations on the transport behaviors of the Lao.33Pro.34Cao.33MnO3(LPCMO). Huge intrinsic tunnel magnetoresistance effects at low field are demonstrated in macroscopic LPCMO thin films etched with periodic antidot arrays. A highest magnetoresistance ratio (about1600%) is achieved at58K, and might originate from delicate phase separation and coherent transport under the applied periodic spatial confinement. Dynamic phase separation is also revealed in such systems due to phase competition. Our findings pave a way to realize tunnel magnetoresistance devices based on electronically phase separated materials with spatial modulations.2. Researches on the effect of light and Au nanoparticles on the transport and magnetic properties of the La0.33Pr0.34Ca0.33MnO3(LPCMO). Au nanoparticles would supress the insulator-metal transition in the LPCMO, while light would induce the insulator-metal transistion in the LPCMO at low temperature. The resistance reduced almost5order at10K after the light illumination, and the lower the temperature, the large change of the resistance. Magnetic and I-V curves measurement reveal that light would transform the charge ordered insulating phase to the ferromagnetic metallic phase, and result in the reduction of the resistance of the LPCMO. By combining the two modulations, light and Au nanopaticles, we might realize the electronic nanofabrication on the manganites.3. Researches on the electronic phase separation in the one dimensional (1D) La0.33Pr0.34Ca0.33MnO3(LPCMO) nanowires. High quality LPCMO has been epitaxial grown on the MgO nanowires. Magnetic and electron spin resonance measurement illustrate that the LPCMO nanowires undergoes a ferromagnetic transformation at low temperature, while the Raman data reveal that the exsitence of the antiferromagnetic phase at low temperature. These results confirmed that the existence of electronic phase separation in the1D manganites nanowires. These findings would shed new light on the researches on the reveal and modulation of the electronic phase separation in manganites under the quantum confined size.