Self-Polarized Spin-Nanolasers
Ju-Ying Chen, Tong-Ming Wong, Che-Wei Chang, Chen-Yuan Dong, and Yang-Fang Chen*
The manipulation of spin in spin-lasers adds a new dimension to develop novel multifunctionality with better performance than their conventional counterparts. However, the rigid requirements of weak spin relaxation and efficient spin injection remain great challenges. Recently, we show that these difficulties can be circumvented by using a new self-polarized spin mechanism. We demonstrate that a high degree of circular polarization of self-polarized spin-nanolasers can be achieved at room temperature in a low magnetic field based on periodic GaN nanorods arrays and Fe3O4 nanoparticles. The unique energy band alignment of Fe3O4 nanoparticles for spin up and spin down electrons spontaneously generates the population imbalance of spin down and spin up electrons in GaN nanorods without an external bias due to selective spin charge transfer. Therefore, electrical pumping by magnetic electrode or optical pumping by circularly polarized light are not required. The methodology shown here can open up a new route to a variety of material systems for the effective generation of spin-lasers covering a wide range of spectrum, which paves a key step for the future development of opto-spintronics.
Figure│Schematics of band alignment of spin-down and spin-up electrons between GaN and Fe3O4. a, Band alignment of spin-down electrons between GaN and Fe3O4. The imperfection of spin orientation of the electrons at the Fermi energy of Fe3O4 is shown explicitly to reflect the true situation. b, Band alignment of spin-up electrons between GaN and Fe3O4. Owing to the population imbalance of spin alignment, the recombination of electron and hole generates spin-polarized emissions. EF, Fermi energy; up and down arrows, spin orientation of the electrons; shaded areas, energy states occupied by electrons; HH+, heavy holes; LH+, light holes.
References:
1.J. Y. Chen, C. Y. Ho, M. L. Lu, L. J. Chu, K. C. Chen, S. W. Chu, W. Chen, C. Y. Mou, and Y. F. Chen*,”Efficient spin-light emitting diodes based on InGaN/GaN quantum disks at room temperature: a new self-polarized paradigm”, Nano Lett. 14, 3130 (2014)
2.Ju-Ying Chen, Tong-Ming Wong, Che-Wei Chang, Chen-Yuan Dong and Yang-Fang Chen*,“Self-polarized spin-nanolasers”, Nature Nanotech. doi:10.1038/nnano.2014.195 (2014)
