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Physical Science Laboratory

Spintronics Research Group

Dr. Akira Fujiwara
Group Leader
Dr. Akira Fujiwara

We investigate to manipulate spin of electrons based on conventional semiconductor technique. We explore spin-based devices utilizing both charge and spin of electrons through the establishment of spin manipulation as well as fundamental spin detection.


The quantized energy levels of electrons in a semiconductor quantum dot (QD) can be easily tuned by controlling the gate voltage, thus enabling us to use a QD as a high-resolution energy analyzer (or spectrometer) for the electrons near the QD. We used this feature of QDs to measure the energy distribution of ballistic nonequilibrium electrons and holes emitted from a quantum wire. Nonequilibrium carriers were emitted by applying a bias voltage (Vpc) to a quantum point contact. The emitted current was again focused by applying a perpendicular magnetic field (B⊥) and analyzed with a QD. When the energy of the nonequilibrium carriers coincides with the quantized energy levels, those carriers can resonantly tunnel through the QD and can be detected as an electric current.