Simultaneous observation of surface- and edge-states of a 2D topological insulator through scanning tunneling spectroscopy and differential conductance imaging

2017 ◽  
Vol 19 (15) ◽  
pp. 9872-9878 ◽  
Author(s):  
Hrishikesh Bhunia ◽  
Abhijit Bar ◽  
Abhijit Bera ◽  
Amlan J. Pal
Keyword(s):  
Topological Insulator ◽  
Fermi Energy ◽  
Topological Insulators ◽  
Dirac Point ◽  
Scanning Tunneling Spectroscopy ◽  
Tunneling Spectroscopy ◽  
Differential Conductance ◽  
Scanning Tunneling ◽  
Edge States ◽  
Simultaneous Observation

Gapless edge-states with a Dirac point below the Fermi energy and band-edges at the interior observed in 2D topological insulators.

Scanning tunneling spectroscopy of a magnetic adatom on graphene

2014 ◽  
Vol 28 (31) ◽  
pp. 1450225 ◽  
Author(s):  
Yang Gao ◽  
Kai-He Ding
Keyword(s):  
Gate Voltage ◽  
Local Density ◽  
Scanning Tunneling Spectroscopy ◽  
Tunneling Spectroscopy ◽  
Differential Conductance ◽  
Scanning Tunneling ◽  
Density Of State ◽  
Tunneling Microscopy ◽  
Substitutional Site ◽  
Kondo Resonance

We present a theoretic study on scanning tunneling spectroscopy (STS) of a magnetic adatom on graphene. Three typical configurations of adatoms on graphene are considered explicitly: the adatom is on the top of a carbon atom (TC), in a substitutional site (SC), or above the center of the honeycomb hexagon (HC). Based on the nonequilibrium Green's function method, we derive the local density of state (LDOS) for the adatom and the differential conductance through the scanning tunneling microscopy (STM) device. Our results show that in comparison with the cases of the TC and SC, there exists an anomalous broadening of the local adatom energy level in the HC, which pushes the adatom energy to first cross the Fermi level, leading to the appearance of an antiresonance in the LDOS due to the interference between the Kondo resonance and the broadened adatom level. Correspondingly, the bias dependence of the differential conductance in the HC exhibits a more asymmetric sharp Kondo peak pinned to the gate voltage, and its height still remains significantly large compared to that for the other two cases. Additionally, with decreasing the gate voltage, the Kondo peak in the differential conductance gradually decays, and eventually vanishes in the absence of the gate voltage.

Dirac States of 2D Topological Insulators: Effect of Heterovalent Dopant-Content

2019 ◽  
Vol 25 (6) ◽  
pp. 1437-1441 ◽  
Author(s):  
Salma Khatun ◽  
Amlan J. Pal
Keyword(s):  
Fermi Energy ◽  
Dirac Point ◽  
Surface States ◽  
Scanning Tunneling Spectroscopy ◽  
Scanning Tunneling ◽  
Metallic State ◽  
X Ray Diffraction ◽  
Dopant Content ◽  
X Ray ◽  
Transmission Electron

AbstractWe have studied Bi2Se3 at its 2D-limit using scanning tunneling spectroscopy (STS). Bulk Bi2Se3 is a well-known topological insulator having gapless surface states. In the 2D limit, the interior of the material exhibits a band gap, whereas the periphery shows a gapless metallic state having a Dirac point. We demonstrate a method to tune the Fermi energy and hence the Dirac point of Bi2Se3 nanoplates through doping at the anionic site. For this purpose, STS measurements were carried out on the Bi2Se3 system. We have used bromide as a dopant, which turns the material to n-type in nature. As a result, STS studies infer that the Fermi energy (EF) shifted toward the conduction band and consequently the Dirac point could be found to move away from Fermi energy. Through STS measurements, we have demonstrated a correlation between the shift of Dirac point position and the dopant content. The size, shape, and compositions of Bi2Se3 nanoflakes and concentration of bromine in the doped nanostructures were determined using transmission electron microscopy, associated energy dispersive X-ray spectroscopy analysis, and X-ray diffraction.

Room temperature differential conductance measurements of triethylamine molecules adsorbed on Si(001)

2016 ◽  
Vol 18 (33) ◽  
pp. 23231-23237 ◽  
Author(s):  
Ahmed Naitabdi ◽  
François Rochet ◽  
Stéphane Carniato ◽  
Fabrice Bournel ◽  
Jean-Jacques Gallet
Keyword(s):  
Room Temperature ◽  
Scanning Tunneling Spectroscopy ◽  
Tunneling Spectroscopy ◽  
Differential Conductance ◽  
Scanning Tunneling ◽  
Temperature Differential

We have measured the differential conductance of the triethylamine molecule (N(CH2CH3)3) adsorbed on Si(001)-2 × 1 at room temperature using scanning tunneling spectroscopy.

Heterovalent substitution in anionic and cationic positions of PbS thin-films grown by SILAR method vis-à-vis Fermi energy measured through scanning tunneling spectroscopy

2016 ◽  
Vol 4 (3) ◽  
pp. 551-558 ◽  
Author(s):  
Hrishikesh Bhunia ◽  
Biswajit Kundu ◽  
Soumyo Chatterjee ◽  
Amlan J. Pal
Keyword(s):  
Thin Films ◽  
Fermi Energy ◽  
Film Formation ◽  
Scanning Tunneling Spectroscopy ◽  
Tunneling Spectroscopy ◽  
Scanning Tunneling ◽  
Heterovalent Substitution ◽  
Silar Method ◽  
Free Carriers ◽  
Element Substitution

Heterovalent element substitution at both ionic sites of PbS achieved during film formation. The dopants introduced free carriers in the semiconductor affecting the Fermi energy, which has been located by STS studies.

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