准二维4×4量子点磁化动力学特性的Monte Carlo模拟

基于Monte Carlo模拟,研究了准二维4×4量子点阵列中交换相互作用常数J、偶极相互作用常数D、磁晶各向异性常数K对自旋组态和相关磁特性的影响。模拟结果表明,量子点阵列和单个量子点表现出完全不同的磁特性,即量子点阵列表现为顺磁性,而单个量子点则为铁磁性;分析不同外磁场下体系自旋组态的变化可以很好地解释模拟结果。     

准二维4×4量子点磁化动力学特性的Monte Carlo模拟(英文)

基于Monte Carlo模拟,研究了准二维4×4量子点阵列中交换相互作用常数J、偶极相互作用常数D、磁晶各向异性常数K对自旋组态和相关磁特性的影响.模拟结果表明,量子点阵列和单个量子点表现出完全不同的磁特性,即量子点阵列表现为顺磁性,而单个量子点则为铁磁性;分析不同外磁场下体系自旋组态的变化可以很好地解释模拟结果.     

Transport and Magnetic Properties of Nanosized La0.6Sm0. 1Sr0.3MnO3 ＋ xCoO Composites

The composites La0.6Sm0.1Sr0.3MnO3 xCoO (x=0.0, 0.1, 0.2, 0.3, 0.4 mol), named as Ax samples, were synthesized by the sol-gel technique to derive homogeneous CoO-coated composites. CoO addition induces an increase of resistivity (ρ) and a decrease of Curie temperature (TC), magnetization, and TP at which the ρ peak is located. It has been concluded that the resistivity below TP fits well with the equation ρ=ρ0 ρ2T2 ρ4.5T4.5, indicating the importance of grain/domain boundary effects, the electron-electron scattering process, and the two magnon scattering process. On the other hand, the paramagnetic insulating region may be explained by using adiabatic small polaron hopping mechanism, thereby indicating that polaron hopping might be responsible for the conduction mechanism. Magnetoresistance results were explained by a two-level model of tunneling MR and percolation model.