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Room-temperature defect-engineered spin filter based on a non-magnetic semiconductor


Generating, manipulating and detecting electron spin polarization and coherence at room temperature is at the heart of future spintronics and spin-based quantum information technology1,2,3,4. Spin filtering, which is a key issue for spintronic applications, has been demonstrated by using ferromagnetic metals5,6,7,8, diluted magnetic semiconductors9,10, quantum point contacts11, quantum dots12, carbon nanotubes13, multiferroics14 and so on. This filtering effect was so far restricted to a limited efficiency and primarily at low temperatures or under a magnetic field. Here, we provide direct and unambiguous experimental proof that an electron-spin-polarized defect, such as a Gai self-interstitial in dilute nitride GaNAs, can effectively deplete conduction electrons with an opposite spin orientation and can thus turn the non-magnetic semiconductor into an efficient spin filter operating at room temperature and zero magnetic field. This work shows the potential of such defect-engineered, switchable spin filters as an attractive alternative to generate, amplify and detect electron spin polarization at room temperature without a magnetic material or external magnetic fields.

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Figure 1: Principle of defect-engineered spin filtering and the experimental approach at room temperature and B=0.
Figure 2: Photoluminescence intensity and polarization (corresponding to the conduction electron spin polarization Pe) with or without the spin-filtering effect.
Figure 3: Dependence of conduction electron spin polarization on the optical excitation power and the concentration of the spin-filtering defects.
Figure 4: Identification of the spin-filtering defects by ODMR.

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W.M.C. and I.A.B. gratefully acknowledge the support from Linköping University through the Professor Contracts, the Swedish Research council (VR), the Swedish Energy Agency, the Knut and Alice Wallenberg Foundation, the Wenner-Gren Foundations and the Swedish Foundation for International Cooperation in Research and Higher Education (STINT). The work at UCSD is partially supported by NSF Grant No. DMR- 0606389.

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Correspondence to I. A. Buyanova or W. M. Chen.

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Wang, X., Buyanova, I., Zhao, F. et al. Room-temperature defect-engineered spin filter based on a non-magnetic semiconductor. Nature Mater 8, 198–202 (2009).

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