题目： Terahertz Talks to Spin: Magentotransport and Magnonics
报告人：金钻明 博士（8455新葡萄场网站物理系）
时间：2017年1月3日 （周二）11：45-13：00
地点： 校本部G309
摘要：Spin-dependent conduction in metals underlies all modern magnetic memory technologies, such as giant magnetoresistance (GMR). According to the fundamental Mott model, the charge current in ferromagnetic transition metals is carried by non-mixing populations of sp-band Fermi-level majority- and minority-spin electrons, experiencing spin-dependent momentum scattering with localized electrons originating from the spin-split d-band. The direct observation of magneto transport under such fundamental conditions, however, requires the conductivity measurements on the ultrafast, sub-100 fs timescale, at which the electron momentum scattering occurs. Here, using ultrafast terahertz spectroscopy on a GMR spin-valve, we directly observe the magneto transport in a metallic system under the fundamental conditions of Mott model. As a result, we are able to directly determine the fundamental parameters of magneto-transport - spin-dependent densities and momentum scattering times of conduction electrons in a ferromagnetic metal. Further, we will discuss the direct excitation, observation, and coherent control of THz-frequency magnons in rare-earth orthoferrites, realized in all-THz experiments.
