Electronic Structure Of Two-dimensional Graphyne Van Der Waals Heterostructures

Two-dimensional(2D)monolayer graphyne(?-GY)is a novel all-carbon material with rich carbon chemical bonds,excellent thermoelectric properties and semiconductor properties.?-GY has potential applications in the energy field of catalysis,hydrogen storage,lithium ion batteries and seawater desalination due to the unique structure and physical properties.2D van der Waals heterostructures based on?-GY and 2D nonmagnetic(or magnetic)materials can also show novel physical properties.The electronic properties of 2D heterostructures can also be adjusted by vertical electric field and biaxial strains,which provides a important theoretical foundation for their designs and applications in nanoelectronic devices.In this dissertation,the electronic structure and Rashba splitting of 2D?-GY/WSe Te heterostructures,tunable electronic structure and magnetic properties of2D?-GY/VI₃ heterostructures and the electronic structure and magnetic characteristics of 2D?-GY/Janus V₂I₃Br₃ heterostructures are studied systematically based on density functional theory.The electronic structure of 2D?-GY/WSe Te heterostructures is calculated.In?-GY/WSe Te heterostructures,the contact types can be affected by different stacking patterns(?-GY/Te WSe heterostructures possess Ohmic contact,while?-GY/Se WTe heterostructures have Schottky contact).At a vertical electric field,the Schottky contact of?-GY/Se WTe heterostructure turns into Ohmic contact.The electric dipole moment and Rashba spin splitting of Janus WSe Te monolayer are increased by covering?-GY layer.Meanwhile,the Rashba spin splitting of?-GY/WSe Te heterostructure can be further tailored by electric field.The electronic structure and magnetic properties of 2D?-GY/VI₃heterostructures are calculated.The results show that semiconductor or half-metallic characteristic of VI₃ monolayer in?-GY/VI₃ heterostructures can be shown due to the difference stacking patterns.The perpendicular magnetic anisotropy(PMA)of VI₃monolayer is enhanced by covering?-GY layer.Biaxial strain and interlayer distance can modulate the electronic structure and magnetic properties of?-GY/VI₃heterostructure.Meanwhile,the interlayer interaction of?-GY/VI₃ heterostructure can be enhanced by decreasing the interlayer distance,which further promotes the charge transfer.The electronic structure of 2D?-GY/Janus V₂I₃Br₃(?-GY/V₂I₃Br₃)heterostructures are investigated.By combing?-GY layer,Janus V₂I₃Br₃ monolayer can shows the half-metallic characteristic.Compared with the pristine Janus V₂I₃Br₃monolayer,the PMA of?-GY/V₂I₃Br₃ heterostructures is enhanced.At a compressive strain of-4%,Janus V₂I₃Br₃ monolayer in?-GY/V₂I₃Br₃ heterostructure realizes the transition from magnetic half-metallic to magnetic metal state.Moreover,the PMA of?-GY/V₂I₃Br₃ heterostructure can be further enhanced by applying compressive strain.