Electronic and Structural Properties of Interfaces in Fe\MgO\Cu-Phthalocyanine Hybrid Structures

The influence of insertion of an ultra-thin Cu-Phthalocyanine (CuPc) between MgO barrier and ferromagnetic layer in magnetic tunnel juctions (MTJs) was investigated. In order to understand the relation between the electronic and structural properties of Fe\MgO\CuPc, the surface (or interface) analysis was carried out systematically by using spin polarized metastable He de-excited spectroscopy for the CuPc films grown on the Si(001)\5 nm MgO(001)\7 nm Fe(001)\1.6 nm MgO(001) multilayer structure as the thickness of CuPc increases from 0 to 5 nm. In particular, for the 1.6 nm CuPc surface, a rather strong spin asymmetry between up-and down-spin band appears while it becomes weaker or disappears for the CuPc films thinner or thicker than similar to 1.6 nm. Our results emphasize the importance of the interfacial electronic properties of organic layers in the spin transport of the hybrid MTJs.