Point and complex defects in monolayer PdSe2: Evolution of electronic structure and emergence of magnetism

Article

关键词: TRANSITION-METAL DICHALCOGENIDES;    PENTA-GRAPHENE;    AIR STABILITY;    SINGLE;    FERROMAGNETISM;    MOSE2;    1ST-PRINCIPLES;    MORPHOLOGY;    BREAKDOWN;    CRYSTAL;   

DOI  :  10.1103/PhysRevB.104.134109

来源: SCIE

【 摘 要 】

Layered transition-metal dichalcogenides (TMDs) constitute an emerging class of materials that provide researchers a platform to realize fundamental studies and to design promising optoelectronic devices. While defects are an almost unavoidable part of TMDs, they bring additional interesting properties absent in defect-free layers. Moreover, the controlled introduction of defects in TMDs makes it possible to tailor the electromagnetic properties of the materials. Here we report defect-induced properties of single-layer PdSe2 and demonstrate the emergence of magnetism at the nanoscale. Our first-principle calculations indicate that Se vacancies create in-gap defect states, which can be responsible for trapping of carriers. The complex square V-Pd(+)4Se vacancy induces spin-polarized states with a total local magnetic moment of 2 mu B per defect, making it possible to introduce magnetization into PdSe2 and therefore expand the family of two-dimensional (2D) magnets. The defect formation energies are much lower compared to many other TMD materials that can explain the presence of a large number of Se defects after mechanical exfoliation of PdSe2 layers, while the central location of the Pd atoms preserves them from exfoliation-induced defect formation. The negatively charged vacancies are prone to form and in many cases demonstrate spin-polarized states. The small diffusion barrier of V-Se in 2D PdSe2 leads to an easy room-temperature migration, while V-pd demonstrates a high diffusion barrier preventing its spontaneous migration. As a guide for experimentalists, we simulate and characterize scanning tunneling microscope images in valence and conduction states and estimate the electron-beam energy for a controllable production of various defect patterns. These intriguing findings make PdSe2 an ideal platform to study defect-induced phenomena.

【 授权许可】

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