scholarly journals Emergence of quasiparticle Bloch states in artificial crystals crafted atom-by-atom

2017 ◽  
Vol 2 (3) ◽  
Author(s):  
Jan Girovsky ◽  
Jose Lado ◽  
Floris Kalff ◽  
Eleonora Fahrenfort ◽  
Lucas Peters ◽  
...  

The interaction of electrons with a periodic potential of atoms in crystalline solids gives rise to band structure. The band structure of existing materials can be measured by photoemission spectroscopy and accurately understood in terms of the tight-binding model, however not many experimental approaches exist that allow to tailor artificial crystal lattices using a bottom-up approach. The ability to engineer and study atomically crafted designer materials by scanning tunnelling microscopy and spectroscopy (STM/STS) helps to understand the emergence of material properties. Here, we use atom manipulation of individual vacancies in a chlorine monolayer on Cu(100) to construct one- and two-dimensional structures of various densities and sizes. Local STS measurements reveal the emergence of quasiparticle bands, evidenced by standing Bloch waves, with tuneable dispersion. The experimental data are understood in terms of a tight-binding model combined with an additional broadening term that allows an estimation of the coupling to the underlying substrate.

1984 ◽  
Vol 37 (4) ◽  
pp. 407
Author(s):  
GP Betteridge

We consider a simple tight-binding model involving all interactions between first and second nearest-neighbour (n.n.) bonds in the diamond lattice. We show that the band structure may be solved analytically in the central approximation in which all second n.n. bond interactions of the same type, for example all bonding: bonding or all bonding: antibonding interactions, are considered equal. The k dependence of the solution is given in terms of the corresponding s-band eigenvalues, which are determined by the topology of the structure.


Symmetry ◽  
2020 ◽  
Vol 12 (7) ◽  
pp. 1076
Author(s):  
Izumi Hase ◽  
Takashi Yanagisawa

A Kene–Mele-type nearest-neighbor tight-binding model on a pyrochlore lattice is known to be a topological insulator in some parameter region. It is an important task to realize a topological insulator in a real compound, especially in an oxide that is stable in air. In this paper we systematically performed band structure calculations for six pyrochlore oxides A2B2O7 (A = Sn, Pb, Tl; B = Nb, Ta), which are properly described by this model, and found that heavily hole-doped Sn2Nb2O7 is a good candidate. Surprisingly, an effective spin–orbit coupling constant λ changes its sign depending on the composition of the material. Furthermore, we calculated the band structure of three virtual pyrochlore oxides, namely In2Nb2O7, In2Ta2O7 and Sn2Zr2O7. We found that Sn2Zr2O7 has a band gap at the k = 0 (Γ) point, similar to Sn2Nb2O7, though the band structure of Sn2Zr2O7 itself differs from the ideal nearest-neighbor tight-binding model. We propose that the co-doped system (In,Sn)2(Nb,Zr)2O7 may become a candidate of the three-dimensional strong topological insulator.


2021 ◽  
Author(s):  
Joy Sharma ◽  
Nishat Mahzabin Helaly ◽  
Mahbub Alam

Abstract In this paper, we have investigated the transport of topological edge states in 2D Zigzag edge Tungsten Ditelluride Nanoribbon (ZTDNR).We have found that zigzag edge nanoribbon (NR) of Tungsten Ditelluride develops topological edge states in the presence of intrinsic spin orbit interaction (SOC). We have used three band tight binding model for the electrons of dz2 , dxy, and dx2 - y2 orbitals with SOC for calculating band structure of NR and Non Equilibrium Greens Function (NEGF) formalism for transport in the NR. We have investigated transport in a pristine device, transport in the presence of a finite potential barrier, transport with constriction within the device and transport with edge imperfections.


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