Influence Of Electronic Structure And Magnetism Of Metal Diffusion Into Tris-(8-hydroquinoline) Aluminum In Organic Semiconductors

Organic spintronics is a new subject of spintronics, which iscombination of organic semiconductor and spintronics. Organicsemiconductors exhibit extremely long spin-relaxation times due tothe weak spin-orbit coupling and negligible hyperfine interaction, so itis an attractive candidate for spintronics applications. In particular,theп-conjugated organic semiconductors tris(8-hydroxyquinoline)aluminum (Alq3) has been found to perform very good in organic spinvalves, providing one of the best giant magnetoresistance (GMR)values. However, in spite of this, it is not understood that significanttunnel magnetoresistance values and so on. Thus the furtherdevelopment of Alq3-based organic spintronics has been greatlyhampered by the existence of these problems. Recently The resultsof experimental studies suggest very little diffusion of metal into Alq3based devices, but it is still unclear whether the observedphenomenon is the influence of magnetoresistance in the devices.In this letter, we employ density-functional theory (DFT) calculations to explore the influence of the electronic and magneticproperties of different metals-diffused the Alq3 mole. We mainlydiscussed the three relatively stable position of metals diffusion, it isnecessary to research influence of different locations on the spinpolarization and the main magnetic mechanism through spin densitydistribution and the density of states. Through the analysis, it is foundthat a type of Na, Al, Ga have one electron in their outer shell ofnon-transition metal, the electron contribution of 2p states of O and Natoms in the quinoline ring leads to formation of local magneticmoments in the system; a type of Mg，Sn have one pair of electronsin their outer shell of non-transition metals, the electron contributionof 3s states of Mg and 2p states of Sn atoms in the quinoline ringleads to formation of local magnetic moments in the system; In a typeof 3d transition metal system the electron contribution of metal 3datom leads to formation of local magnetic moments. Furthermore weexplore the influence of the electronic and magnetic properties ofdifferent metals-diffused the Alq3 organic semiconductor and havesome regular conclusions, which may have a major impact on thespin-dependent effects in the organic spin electronics research.