The Effect Of Organic Molecular Structure Modulation On The Spin Polarization Of The Organic/ferromagnetic Interface

In the past decades,spintronics has got lots of interests as a potential research area of condensed physics.In recent years,one of the amazing progresses in this field is the rise of the organic spintronics.Organic spintronics is a promising field in developing cheap and soft spintronics devices.In this field,interfacial spin polarization(SP)at organic interface is an important issue,which plays a key role in determining the spin injection efficiency and the spin-polarized transport property in organic devices.Unlike rigid inorganic interfaces,a merit of organic interface is that chemical adsorption of the organic molecule onto the ferromagnetic surface is possible,where orbital hybridization between the molecule and the ferromagnetic atom happens.The orbital hybridization may modify the interfacial SP quite different from the bulk ferromagnet,or even an opposite SP.Thus the design of organic interfacial SP becomes possible by adjusting the interfacial details,which has attracted more and more interests and even triggered a new field called “organic spinterface”.Besides the electrode and the details of the interface coupling,one of the important factors which affect the interfacial spin polarization is the molecular structure.Modulation of the molecular structure will change the nature of the molecular orbitals,which can affect the interfacial orbital hybridization between organic molecule and ferromagnetic surface.In this paper,we mainly research modulation of organic interfacial spin polarization by molecular structure.In this article,we mainly research the benzene/Ni interface.Based on ab-initio theory,we theoretically investigated the SP at molecule/Ni interface with different terminal anchoring groups and side groups.Conclusions of our paper are given as follows:1.Based on ab initio theory,here we proposed a spin selection at organic interface via anchoring group by adsorbing a benzene molecule onto Ni(111)surface,such as-SH,-OH,and-CN.The results demonstrate that either a positive or negative interfacial spin polarization may be obtained by choosing different anchoring groups.The orbital analysis via the projected density of states shows that the interfacial spin polarization is sensitive to the hybridization of the outer orbital of the anchoring atom as well as its energy relative to the d orbital of the ferromagnetic atom.The work indicates a feasible way to realize spin selection at the organic spinterface by anchoring group.2.Based on ab initio theory,benzene molecule with different side groups flatly adsorbed onto Ni(111)surface,such as-H,-NO2,and-NH2.The results indicate that the side group can affect the magnitude of the SP of the organic spinterface.Furthermore,the side groups change the symmetry of benzene molecule,and then modify the orbital hybridization between the molecule and the ferromagnet,which changes the SP of the organic spinterface.The work indicates the side groups can change the symmetry of benzene molecule,and effect the interfacial spin polarization.