Berlin 2015 – wissenschaftliches Programm

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MA: Fachverband Magnetismus

MA 7: Magnetic Semiconductors

MA 7.4: Vortrag

Montag, 16. März 2015, 12:15–12:30, EB 202

Formation of stable bound magnetic polarons in depleted magnetic ZnO films — •Heidemarie Schmidt¹, Tim Kaspar¹, D. Bürger¹, I. Skorupa^1,2, S. Zhou², C. Timm³, and O.G. Schmidt^1,4 — ¹TU Chemnitz — ²HZDR — ³TU Dresden — ⁴IFW Dresden

The clear understanding of transport and optical properties of magnetic transition-metal oxides (TMO) in an external magnetic and electric field [1] is important for future transparent spintronics. To explain room-temperature ferromagnetism in intrinsically n-type conducting, magnetic TMO, Coey et al. [2] have proposed a ferromagnetic exchange mechanism involving oxygen vacancies, which form F-centers with two trapped electrons. The increase of the low-frequency dielectric constant of magnetic oxides with increasing concentration of isovalent magnetic ions has been neglected so far. Therefore, the reported necessary concentration of oxygen vacancies for percolating BMPs in magnetic oxides is overestimated. We have investigated the magnetic properties of ZnO thin films with stable BMPs and have adapted the existing hydrogenic BMP model to oxygen vacancies, which form F+ centers with one trapped electron [3]. Magnetic oxides with stable BMPs will allow for new device approaches which exploit the huge internal magnetic fields felt by charge carriers in magnetic oxide films with F+-center BMPs. [1] Q. Xu, H.S. et al., Phys. Rev. Lett. 101 (2008), Jpn. J. Appl. Phys. 49 (2010), [2] J.M.D. Coey et al., Nat. Mat. 4 (2005), [3] T. Kaspar, H.S. et al., IEEE Elec. Dev. Lett. 34 (2013); Appl. Phys. Mat. 2 (2014)