MODELING AND EXPERIMENT OF THE INFLUENCE OF GRAIN SIZE TO THE PROPERTIES OF La0.7Sr0.3MnO3

• Main Author: FREDY NAA (NIM: 30211005), CHRISTIAN
• Format: Dissertations
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/21508
• Institution: Institut Teknologi Bandung

This thesis is devoted to study the influence of grain size to the magnetic and magnetoresistance properties of manganese perovskite in particular La0.7Sr0.3MnO3(LSMO). The study is conducted in both modeling and experiment. The main contribution of this thesis is to give insight to the physics of grain size in LSMO perovskite, mainly the micro state of the magnetic properties. For modeling, we propose the general model of Giant Magnetoresistance by using one-dimensional multiple barrier potential. By using this model, we are able to include all potentials that involve in magnetoresistance. We also use the extended Ising model and Monte Carlo method. By using this model, we are able to model the Double Exchange mechanism. To model the grain size, we propose grain-like model that also is an extension of Ising model. We present the modeling results: magnetization, magnetic properties of core and surface, zero field cooled and field cooled properties, susceptibility, specific heat and magnetoresistance properties. We compare those results with experiment from some related references. For experiment, we use sol-gel method to synthesize the LSMO nano powder and thin film in different grain size. By altering the sintering temperature, we were able to modified the grain size of LSMO. We studied the physical, magnetic, magnetoresistance and magneto relaxation properties.