Lin Yingbin

Effect of C doping on the structural and electronic properties of LiFePO4: A first-principles investigation

Using first-principles calculations within the generalized gradient approximation (GGA) +U framework, we investigate the effect of C doping on the structural and electronic properties of LiFePO4. The calculated formation energies indicate that C doped at O sites is energetically favoured, and that C dopants prefer to occupy O3 sites. The band gap of the C doped material is much narrow than that of the undoped one, indicating better electro- conductive properties. To maintain charge balance, the valence of the Fe nearest to C appears as Fe3+, and it will be helpful to the hopping of electrons.

Enhanced Magnetoresistance of (La0.67Ca0.33MnO3) Composites Coated by Zn0.95Co0.05O

La0.7Ca0.3MnO3:xZn0.95Co0.05O (x = 0.0, 0.05, 0.1, 0.15 mol) composites are prepared by a sol-gel process. X-ray diffraction and energy diffraction spectroscopy reveal that there is no evidence of a reaction between the La0.7Ca0.3MnO3 (LCMO) and Zn0.95 Co0.05 O (ZCO). Magnetization M, Curie temperature TC and metal-insulator transition temperatures Tp are observed to decrease with increasing ZCO content. Compared with x = 0.0, a great enhancement in the magnetoresistance (MR) is observed at around TC for x = 0.05, 0.10, 0.15. Based on the tunneling MR and percolation models, this great change of MR is well explained.

Numerical Calculation of Kerr Spectra for Magnetic Granular Films

Based on the 4×4 matrix method, we present theoretical calculations of the magneto-optic polar Kerr effect with the incident energy in granular films. It is found that the simulated results are in good agreement with experimental ones. In addition, Kerr rotation and ellipticity as functions of incident angle and magnetic film thickness have been computed. The calculated results indicate that the Kerr spectra as a function of the incident angle reveal a maximum at certain incident angles and the Kerr spectra appear to be periodical and have damped oscillation as a function of the magnetic film thickness, which is important for the design of the materials in the future.