张国平教授
美国印第安纳州立大学
时间: 5月13日10点
地点: 唐仲英楼A213
ABSTRACT: It has been known for twenty years that an ultrafast laser pulse can affect the magnetic properties. This is the beginning of the era of femtomagnetism, where the magnetic properties undergo a dramatic change. Now, the demagnetization is observed and confirmed, and more interestingly, a single laser pulse, without any assistance of the magnetic field, can switch spin. This potentially has some important applications in ultrafast magnetic storage. However, its underlying mechanism is controversial. Is it a thermal or nonthermal process? In this talk, I will first give a brief overview of the field. In particular, I will explain how the magneto-optics signal is correlated with the magnetic property change. Then I will examine the possibility to use mechanic pressure to influence the dynamics. The role of the exchange interaction will be discussed. Finally, I will report some of the latest results in the exchange pulse and its effect on the spin switch.
Dr. Guoping Zhang is professor of physics at Indiana State University and has been a Promising Scholar at Indiana State University. Dr. Zhang's research interests include femtosecond magnetism, nano-material engineering, nanostructures, fullerenes, spintronics, nonlinear optics in conjugated polymers, strongly correlated electron systems, ultrafast spectroscopy, pump-probe and four-wave mixing signal, laser-induced ultrafast spin dynamics in nano and low dimensional magnets, soft x-ray spectroscopy, high harmonic generations, mechanic properties of diamondoids, superconductivity in MgB2, and photoisomerization in rhodopsin.