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748 results on '"Lv, Pengfei"'

11. Electronic properties and quantum transports in functionalized graphene Sierpinski carpet fractals

Author

Yang, Xiaotian, Zhou, Weiqing, Yao, Qi, Lv, Pengfei, Wang, Yunhua, and Yuan, Shengjun

Subjects
Condensed Matter - Mesoscale and Nanoscale Physics
Abstract

Recent progress in controllable functionalization of graphene surfaces enables the experimental realization of complex functionalized graphene nanostructures, such as Sierpinski carpet (SC) fractals. Herein, we model the SC fractals formed by hydrogen and fluorine functionalized patterns on graphene surfaces, namely, H-SC and F-SC, respectively. We then reveal their electronic properties and quantum transport features. From calculated results of the total and local density of state, we find that states in H-SC and F-SC have two characteristics: (i) low-energy states inside about |E/t|<1 (with t as the near-neighbor hopping) are localized inside free graphene regions due to the insulating properties of functionalized graphene regions, and (ii) high-energy states in F-SC have two special energy ranges including -2.3

Published
2021
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32. Strain-induced semiconductor to metal transition in MA2Z4 bilayers

Author

Zhong, Hongxia, Xiong, Wenqi, Lv, Pengfei, Yu, Jin, and Yuan, Shengjun

Subjects
Condensed Matter - Materials Science
Abstract

Very recently, a new type of two-dimensional layered material MoSi2N4 has been fabricated, which is semiconducting with weak interlayer interaction, high strength, and excellent stability. We systematically investigate theoretically the effect of vertical strain on the electronic structure of MA2Z4 (M=Ti/Cr/Mo, A=Si, Z=N/P) bilayers. Taking bilayer MoSi2N4 as an example, our first principle calculations show that its indirect band gap decreases monotonically as the vertical compressive strain increases. Under a critical strain around 22%, it undergoes a transition from semiconductor to metal. We attribute this to the opposite energy shift of states in different layers, which originates from the built-in electric field induced by the asymmetric charge transfer between two inner sublayers near the interface. Similar semiconductor to metal transitions are observed in other strained MA2Z4 bilayers, and the estimated critical pressures to realize such transitions are within the same order as semiconducting transition metal dichalcogenides. The semiconductor to metal transitions observed in the family of MA2Z4 bilayers present interesting possibilities for strain-induced engineering of their electronic properties.

Published
2020
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33. Multi-ultraflatbands tunability and effect of spin-orbit coupling in twisted bilayer transition metal dichalcogenides

Author

Zhan, Zhen, Zhang, Yipei, Lv, Pengfei, Zhong, Hongxia, Yu, Guodong, Guinea, Francisco, Silva-Guillen, Jose Angel, and Yuan, Shengjun

Subjects
Condensed Matter - Mesoscale and Nanoscale Physics
Abstract

Ultraflatbands that have been theoretically and experimentally detected in a bunch of van der Waals stacked materials showing some peculiar properties, for instance, highly localized electronic states and enhanced electron-electron interactions. In this Letter, using an accurate tight-binding model, we study the formation and evolution of ultraflatbands in transition metal dichalcogenides (TMDCs) under low rotation angles. We find that, unlike in twisted bilayer graphene, ultraflatbands exist in TMDCs for almost any small twist angles and their wave function becomes more localized when the rotation angle decreases. Lattice relaxation, pressure and local deformation can tune the width of the flatbands, as well as their localization. Furthermore, we investigate the effect of spin-orbit coupling on the flatbands and discover spin/orbital/valley locking at the minimum of the conduction band at the K point of the Brillouin zone. The ultraflatbands found in TMDCs with a range of rotation angle below $7^\circ$, may provide an ideal platform to study strongly correlated states., Comment: 6 pages, 4 figures

Published
2020
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46. Study on Seepage and Mass Transfer Characteristics During CO2 Storage in Saline Aquifer

Author

Zhang, Weixin, Wu, Bohao, Lv, Pengfei, Li, Shaohua, Jiang, Lanlan, di Prisco, Marco, Series Editor, Chen, Sheng-Hong, Series Editor, Vayas, Ioannis, Series Editor, Kumar Shukla, Sanjay, Series Editor, Sharma, Anuj, Series Editor, Kumar, Nagesh, Series Editor, Wang, Chien Ming, Series Editor, Sun, Baojiang, editor, Sun, Jinsheng, editor, Wang, Zhiyuan, editor, Chen, Litao, editor, and Chen, Meiping, editor

Published
2022
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