A joint research group led by Professor Masaaki Tanaka and his colleagues at the University of Tokyo and RIKEN has succeeded for the first time in increasing the magnetization of a semiconductor quantum well structure containing ferromagnetic semiconductors (In, Fe)As at ultrafast rates of 600 femtoseconds, or subpicoseconds, by irradiating it with a very short pulse laser beam. This ultrafast magnetization control is not based on conventional carrier concentration changes, but is a revolutionary control of the wave function engineering in semiconductors, and this is the first demonstration of such a control by wave function engineering. This achievement is expected to lead to spintronics devices and quantum devices that can operate at ultrahigh speed and ultra-low power consumption in the terahertz frequency band.
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