The Theoretical Research Of Spin-dependent Tunneling Properties Of Graphyne-based Molecular Spintronics Devices

The advancements of performance of electronic products are ascribed to the development of chips.With the further reduction in the size of these electronic devices,the emergence of quantum effects,such as electron interference,tunneling,and diffraction,has made Moore's Law to face a crisis of failure.One of the answers to solve this issue is molecular spintronics device.On the one hand,molecular spintronic devices avoid the negative effects of quantum effects;on the other hand,molecular spintronics aims to manipulate electron's spin degree as well as charge degree in molecular devices and provide a more precise insight into quantum transport properties at molecular level.The interaction among spin electrons is 1000 times weaker than that among charge electrons.This advantage results in that the spintronic devices have lower energy consumption and higher stability than traditional microelectronic devices.As a result,exploring the spin-dependent transport properties of molecular spintronic devices can provide potential applications for nanoelectronics and spintronics.The electronic,magnetic properties of Z?GYNRs and the transport properties of corresponding homojunctions are theoretically investigated in present study.The results show that the properties of Z?GYNRs can be effectively modulated by substitution of O,B or N atoms.The Z?GYNR homojunctions can exhibit rich transport properties such as tunneling magnetoresistance(TMR),negative differential resistance(NDR),abnormal magnetoresistance(AMR)and spin-filtering effects.After O,B or N substitution,the transport properties of homojunctions are enhanced.Although the Z?GYNR homojunctions have intriguing transport properties,the TMR and SPR need to be improved furtherly.Therefore,we introduced molecular magnetic tunnel junctions(MMTJs).In present study,we are aimed at designing a novel kind of spintronic device with graphyne and graphene nanoribbons,i.e.,the molecular magnetic tunnel junctions(MMTJs),and investigating its spin-dependent transport properties and the spin-polarized optoelectronic properties.Our results show that two kinds of MMTJs have different microscopic transport mechanisms.Significant single or dual spin-filtering effects,giant TMR and spin NDR can be observed in the MMTJs.In addition,the spin-polarized optoelectronic properties of the MMTJs are dependent on the polarization direction of light and magnetization directions of the electrodes.Apart from?-graphyne-based MMTJs,in the third part,we designed two kinds of novel molecular spintronic devices with 6,6,12-graphyne and ZGNRs,and studied their spin-filtering effect and TMR effect.Our results show that two different net spin currents can be obtained by tuning the spin configurations and the maximal order of magnitudes of tunneling magnetoresistance values of the two MMTJs reaches 10~6%.The high SPR and large TMR value provide high sensitivity for practical applications.