scholarly journals Alkali-metal induced band structure deformation investigated by angle-resolved photoemission spectroscopy and first-principles calculations

2018 ◽  
Vol 97 (15) ◽  
Author(s):  
S. Ito ◽  
B. Feng ◽  
M. Arita ◽  
T. Someya ◽  
W.-C. Chen ◽  
...  
Keyword(s):  
Alkali Metal ◽  
Band Structure ◽  
First Principles ◽  
Photoemission Spectroscopy ◽  
First Principles Calculations ◽  
Structure Deformation ◽  
Angle Resolved Photoemission Spectroscopy

scholarly journals Band Topology of Bismuth Quantum Films

Crystals ◽  
2019 ◽  
Vol 9 (10) ◽  
pp. 510 ◽  
Author(s):  
Tay-Rong Chang ◽  
Qiangsheng Lu ◽  
Xiaoxiong Wang ◽  
Hsin Lin ◽  
T. Miller ◽  
...  
Keyword(s):  
Band Structure ◽  
First Principles ◽  
Quantum Confinement ◽  
Energy Gap ◽  
Photoemission Spectroscopy ◽  
Topological Phase ◽  
Direct Visualization ◽  
First Principles Calculations ◽  
Angle Resolved Photoemission Spectroscopy ◽  
Theoretical Results

Bismuth has been the key element in the discovery and development of topological insulator materials. Previous theoretical studies indicated that Bi is topologically trivial and it can transform into the topological phase by alloying with Sb. However, recent high-resolution angle-resolved photoemission spectroscopy (ARPES) measurements strongly suggested a topological band structure in pure Bi, conflicting with the theoretical results. To address this issue, we studied the band structure of Bi and Sb films by ARPES and first-principles calculations. The quantum confinement effectively enlarges the energy gap in the band structure of Bi films and enables a direct visualization of the Z 2 topological invariant of Bi. We find that Bi quantum films in topologically trivial and nontrivial phases respond differently to surface perturbations. This way, we establish experimental criteria for detecting the band topology of Bi by spectroscopic methods.

scholarly journals Intrinsic magnetic topological insulator phases in the Sb doped MnBi2Te4 bulks and thin flakes

2019 ◽  
Vol 10 (1) ◽  
Author(s):  
Bo Chen ◽  
Fucong Fei ◽  
Dongqin Zhang ◽  
Bo Zhang ◽  
Wanling Liu ◽  
...  
Keyword(s):  
First Principles ◽  
Magnetic Order ◽  
Photoemission Spectroscopy ◽  
First Principles Calculations ◽  
New Device ◽  
Angle Resolved Photoemission Spectroscopy ◽  
Potential Applications ◽  
Device Applications ◽  
Physical Phenomena ◽  
Promising Avenue

Abstract Magnetic topological insulators (MTIs) offer a combination of topologically nontrivial characteristics and magnetic order and show promise in terms of potentially interesting physical phenomena such as the quantum anomalous Hall (QAH) effect and topological axion insulating states. However, the understanding of their properties and potential applications have been limited due to a lack of suitable candidates for MTIs. Here, we grow two-dimensional single crystals of Mn(SbxBi(1-x))2Te4 bulk and exfoliate them into thin flakes in order to search for intrinsic MTIs. We perform angle-resolved photoemission spectroscopy, low-temperature transport measurements, and first-principles calculations to investigate the band structure, transport properties, and magnetism of this family of materials, as well as the evolution of their topological properties. We find that there exists an optimized MTI zone in the Mn(SbxBi(1-x))2Te4 phase diagram, which could possibly host a high-temperature QAH phase, offering a promising avenue for new device applications.

scholarly journals Mechanical properties and band structure of CdSe and CdTe nanostructures at high pressure - a first-principles study

2019 ◽  
Vol 13 (2) ◽  
pp. 124-131 ◽  
Author(s):  
Natarajan Kishore ◽  
Veerappan Nagarajan ◽  
Ramanathan Chandiramouli
Keyword(s):  
Mechanical Properties ◽  
High Pressure ◽  
Shear Modulus ◽  
Band Structure ◽  
First Principles ◽  
Pressure Range ◽  
Uniaxial Pressure ◽  
First Principles Calculations ◽  
Zinc Blende ◽  
Cauchy Pressure

First-principles calculations for CdSe and CdTe nanostructures were carried out to study their mechanical properties and band structure under the uniaxial pressure range of 0 to 50GPa. It was presumed that the CdSe and CdTe nanostructures exist in the zinc-blende phase under high pressure. The mechanical properties, such as elastic constants, bulk modulus, shear modulus and Young?s modulus, were explored. Furthermore, Cauchy pressure, Poisson?s ratio and Pugh?s criterion were studied under high pressure for both CdSe and CdTe nanostructures, and the results show that they exhibit ductile property. The band structure studies of CdSe and CdTe were also investigated. The findings show that the mechanical properties and the band structures of CdSe and CdTe can be tailored with high pressure.

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