Magnetic Semiconductor EuO, EuS, and EuSe Nanocrystals for Future Optical Devices

Magnetic semiconductor nanocrystals composed of lanthanoid ions, europium chalcogenide nanocrystals (EuX: EuO, EuS, and EuSe nanocrystals), are characterized by the narrow 4f orbitals that exist as degenerate levels between the conduction band [5d orbitals of Eu(II)] and the valence band (p orbitals of O2-, S2-, and Se2-). In this review, syntheses and characteristic photophysical properties of EuX nanocrystals are introduced. EuX nanocrystals are expected to be useful in applications such as future optical isolators, optomagnetic and spintronic devices.