The Study Of Charge Injection And Transport Under The External Electric Field In Ferromagnetic / Polymer Muti-layer Structure

Since seventies of last century, the doped low-dimensional organic polymer was found to have conducting properties, organic conducting polymers have attracted much attention to material researchers because of its good physical properties of electrical,optical and magnetic, as well as of the unique chemical properties of plasticity and light weight. Afterwards a large number of scholars from both experimental and theoretic respects conducted extensive researches and discussions on physical substructure of its carrier, conductive mechanism, the light-emitting mechanism and magnetic effects of organic conducting polymers.The study has shown that the difference between organic conducting polymers and inorganic materials is that the carriers are not traditional electron or hole, but rather the soliton, polaron, bipolaron and so on. Only the neutral soliton and polaron carry spin, the others don't carry spin.Due to the discovery of giant magneto-resistance and tunnel magneto-resistance in near decade, a revolution in magnetic storage and magnetic recording has been triggered,which resulting in the birth of a new discipline around the spin transport and spin control-spintronics. As the organic semiconductor material with the hyperfine interaction and the weak spin-orbit coupling, spin diffusion length is relatively long, so it is an ideal candidate material for spin-polarized transport. So far the research on organic spintronics is just beginning, some phenomena about spin are predicted in theory, and organic spin-polarized current can be present was also confirmed in experiments. The main research work of the thesis is as follows:1. In the third chapter, by considering ferromagnetic metal / polyacetylene /ferromagnetic metal structure, we investigated the effect of interface coupling constants,ferromagnetic atoms spin splitting strength, electron- electron interaction on spin-polarized injection and carriers' transformation in the system respectively by using extended SSH model. The study found that,with the interface coupling constants increasing, the spin polarization of organic layer increase, and the depth of polarization remains unchanged. Both ferromagnetic atoms spin splitting strength and electron-electron interaction have an important influence on carrier transformation in system, if they continue to increase, no-spin bipolaron would change to spin polaron.2. In the fourth chapter, by considering ferromagnetic meltal / polyacetylene /ferromagnetic metal / polyacetylene / ferromagnetic metal structure, we investigated thetransport of carriers in system under external electric field. The study found that, if the ferromagnetic metal / polyacetylene system under external electric field, spin polaron would transfer between two organic layers, in other words, the system could conduct spin polarization in the whole chain.