Structure and transport properties of Y and Sr co-doped La2/3-xYxCa1/3-ySryMnO3

• 1、Lab of Solid State Microstructures, Nanjing University
• 2、Lab of Solid State Microstructures- Nanjing University

Abstract：X-ray diffraction with the Rietveld refinements was used to characterize the structure and the atomic parameters of the samples of the nominal composition of La2/3-xYxCa1/3-ySryMnO3 (LYCSMO). There is only one phase that has been detected with the dopants of Y and Sr with x  0.20 or y0.19. The lattice parameters along a-, b-, and c-direction remain almost unchanged with x0.20. The bond angle of Mn-O-Mn increases from 151.9° for x=0 to 172.7° for x=0.20, which indicates that the symmetry of MnO6 octahedragonal increases with increasing x. The metal-to-insulator transition temperature, Tc, decreases with increasing the Y content with x  0.10 while Tc increases slightly with further increasing x. The Y content dependence of magnetoresistance shows a parabolic behavior. The maximum MR value corresponds to x=0.08~0.10. A percolation model was used to fit the magnetotransport behavior for all samples.

Keywords： Y,Sr co-doping, La2/3Ca1/3MnO3, Crystal structure, polaron