In the future, ultrahigh-speed spintronics will require ultrafast coherent magnetization reversal within a picosecond -- one-trillionth of a second. Spintronics centers on an electron's spin and magnetic moment in solid-state devices. While this may eventually be achieved via irradiation with a nearly monocyclic terahertz pulse, the small change of magnetization, or modulation, it generates has so far prevented any practical application of this technique.
Generally, the "magnetic field" component of a terahertz pulse is considered to be the origin of the coherent terahertz response of the magnetization. But, as a group of University of Tokyo researchers previously discovered, the "electric field" component of a terahertz pulse plays a key role in the terahertz magnetization modulation of semiconductor-based ferromagnetic materials.
Now the group reports in the journal Applied Physics Letters, from AIP Publishing, that their initial discovery inspired them to explore ferromagnetic nanoparticles embedded within a semiconductor. Their theory was that the electric field of the terahertz pulse could be effectively applied to each nanoparticle due to the small energy loss of the terahertz pulse during its propagation through a semiconductor.
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