Zun Xie

Ab initio Study of Geometries and Magnetic Properties of Small Co Clusters

The lowest-energy geometric and isomers of freestanding Con clusters (n = 2-13) and their corresponding magnetic moments have been systematically studied using the first principles (DMol method) based on the density-functional theory. The calculated results show that the Jahn-Teller effect plays an important role in the process because there are many isomers near the ground state. The difference of magnetic moment is in general very similar between the global minima and the second isomers. The second derivative of binding energy shows strong odd-even alternation and that the 6-, 10- and 12- atom cluster are all magic.

The step effect of hysteresis loop in FM/AFM mixed magnetic system

By using statistical analysis and Monte Carlo simulation, we investigate the nature of step effect in the hysteresis loop with ±J Ising model and Heisenberg model respectively. The results indicate that it is the strong anisotropy, weak magnetic dipolar interaction, and low temperature that together induce the step effect of ferromagnetic (FM) and antiferromagnetic (AFM) mixed magnetic system, and the results are in good agreement with experiments phenomenally. That makes us view spin glass and magnetic sensor from a new aspect.