خواص ساختاري ، الكتريكي و مغناطيسي منگنايت La1-x Cax Mno3

The structural, electrical and magnetic properties of La1-x Cax MnO3 Manganite

Manganites are considered as subbranches of condensed matter physics with a great wealth of physical mechanisms. In this investigation we have studied the structural, electrical and magnetic properties of a series of LaL_XCa,MnO3 manganite with x=0.1, 0.2, ...,0.5. We observed that the crystal structure of this manganite, with small dopping, at room temperature is orthorhombic and by increasing the amount of dopping, its structure changes towards tetragonal. Also, by increasing calcium clopping a metallic phase induction occurs at low temperature and also a metal-insulator transition occurs at the samples Curie temperature. By increasing the amount of dopping to 0.5 the metalic-insulator transition temperature and the Curie temperature of the samples both increase first and then decrease. We suggest a theoretical model with which we can interpret qualitatively many properties of manganites, such as their metal-insulator phase transition and their colossal magnetoresistance.