The effect of MgO barrier on the structure and magnetic properties of Co2MnSi films on n-Si(100) substrates

We investigated the structure and magnetic properties of Co2MnSi/MgO/n-Si(100) films with the goal of achieving efficient spin injection. The Co2MnSi films were fabricated by dc sputtering and post annealed at 400 degrees C for 1 h. They were oriented along the < 100 > direction with a MgO barrier layer. A strong chemical reaction was observed between the Co2MnSi thin films and n-Si substrates in the absence of the MgO barrier. The diffusion or chemical reaction may occur up to a MgO layer thickness of 2 nm. With a MgO layer that is 2 nm thick, Co2MnSi possessed large saturation magnetization and low surface roughness at room temperature. The electrical (I-V) characteristics of Co2MnSi/MgO(2 nm)/n-Si(100) obtained at various junction sizes were symmetric, suggesting that MgO was an effective tunnel barrier. (C) 2009 American Institute of Physics. [doi:10.1063/1.3260253]