Effect of the s ,p-d exchange interaction on the excitons in ZnCoO epilayers - Archive ouverte HAL Access content directly
Journal Articles Physical Review B: Condensed Matter and Materials Physics (1998-2015) Year : 2006

Effect of the s ,p-d exchange interaction on the excitons in ZnCoO epilayers

Abstract

We present a spectroscopic study of ZnCoO layers grown by molecular beam epitaxy on sapphire substrates. ZnCoO is commonly considered as a promising candidate for being a Diluted Magnetic Semiconductor ferromagnetic at room temperature. We performed magneto-optical spectroscopy in the Faraday configuration, by applying a magnetic field up to 11T, at temperatures down to 1.5K. For very dilute samples (x<0.5%), the giant Zeeman splitting of the A and B excitons is observed at low temperature. It is proportional to the magnetization of isolated Co ions, as calculated using the anisotropy and g-factor deduced from the spectroscopy of the d-d transitions. This demonstrates the existence of spin-carrier coupling. Electron-hole exchange within the exciton has a strong effect on the giant Zeeman splitting observed on the excitons. From the effective spin-exciton coupling, =0.4eV, we estimate the difference of the exchange integrals for free carriers, N0 |alpha - beta|=0.8=eV. The magnetic circular dichroism observed near the energy gap was found to be proportional to the paramagnetic magnetization of anisotropic Co ions even for higher Co contents.

Dates and versions

hal-00021923 , version 1 (29-03-2006)

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Wojciech Pacuski, David Ferrand, Joel Cibert, Christiane Deparis, Jan A. Gaj, et al.. Effect of the s ,p-d exchange interaction on the excitons in ZnCoO epilayers. Physical Review B: Condensed Matter and Materials Physics (1998-2015), 2006, 73, pp.035214. ⟨10.1103/PhysRevB.73.035214⟩. ⟨hal-00021923⟩
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