14581

1376 دكتري

دكتري

ماده چگال

اصفهان : دانشگاه صنعتي اصفهان

1397

يازده، 140ص.:مصور،جدول

فرهاد فضيله

فرهاد شهبازي

اسماعيل عبدالحسيني سارسري، محمد مرداني، غلامرضا ارشدي

1398/02/09

كتابنامه

فيزيك

فيزيك

1398/02/10

2528790

Tight binding investigation of the electronic properties of phosphorene and phosphorene nanoribbons Esmaeil Taghizadeh Sisakht etsisakht28@gmail com January 14 2019 Department of Physics Isfahan University of Technology Isfahan 84156 83111 Iran University Code IUT 77142 Degree Ph D Language Farsi supervisor Dr Farhad Fazileh fazileh@cc iut ac ir Abstract In this thesis we will theoretically investigate the low energy electronic properties of monolayer phosphorene using the tight binding approach We will specially focus on the topological properties of this system To investigate these topological features we will first review the basic theories of systems with and without time reversal symmetry Also we will introduce efficient numerical methods for computing rele vant topological invariants which are very useful for characterization of the topology of complicated band structures We will numerically implement these methods to well known models and compare the obtained topological phase diagrams with an alytic results to demonstrate the validity of our algorithm Then we will start by introducing the tight binding TB model of monolayer phosphorene MLP The band structure and effective masses of MLP near the gap are presented based on the TB model and it is shown that the dispersion is relativistic along the armchair direction Thereafter numerical data for this model are presented for zigzag and armchair phosphorene nanoribbons and the emergence of flat bands in zigzag phos phorene nanoribbons is discussed The scaling behavior of band gaps with ribbon width is presented and the obtained results are compared with those of the other methods Next the behavior of MLP in the presence of a perpendicular magnetic field which breaks the time reversal symmetry is discussed Our goal is to address the debating field dependence of Landau levels in MLP Using a simple approach we will demonstrate that the Landau levels dependence on magnetic field is indeed as for conventional 2D semiconductor electron gases We show that the results are valid up to very high field regime Then we will discuss the conditions for which such a dependence can continuously evolve into another field dependences Finally the effective low energy TB model Hamiltonian including the SOC terms for MLP is obtained Then we will study the effect of axial strains on the band structure produced by this model and our results are compared with DFT results We will show a topological phase transition in the electronic properties of phosphorene in the presence of particular types of strain and the characteristics of corresponding edge states in zPNRs will be discussed Keywords black phosphorus phosphorene tight binding model phosphorene nanoribbons topologicalinsulators landau levels strain Z2 invariant

فرهاد فضيله

فرهاد شهبازي

اسماعيل عبدالحسيني سارسري، محمد مرداني، غلامرضا ارشدي