Related Experiment Video
Updated: Feb 27, 2026
05:39
Scalable Quantum Integrated Circuits on Superconducting Two-Dimensional Electron Gas Platform
Published on: August 2, 2019
10.4K
Excitonic gap generation in thin-film topological insulators
Natália Menezes1, C Morais Smith1, Giandomenico Palumbo1
1Institute for Theoretical Physics, Center for Extreme Matter and Emergent Phenomena, Utrecht University, Princetonplein 5, 3584CC Utrecht, Netherlands.
Summary
We analyzed excitonic gap generation in topological insulators. Strong coupling leads to dynamical mass generation for excitonic states, altering critical flavor numbers for exciton condensation.
Area of Science:
- Condensed matter physics
- Topological insulators
- Quantum field theory
Background:
- Topological insulators possess unique surface states with potential for novel electronic phenomena.
- Excitonic gap generation is crucial for understanding emergent electronic phases in materials.
- Strong coupling effects are key to observing exotic quantum phenomena.
Purpose of the Study:
- To investigate excitonic gap generation in 3D topological insulators under strong coupling.
- To analyze the role of effective gauge theories in describing these phenomena.
- To understand the impact of dynamical interactions on symmetry breaking and mass generation.
Main Methods:
- Projection of 3D+1D quantum electrodynamics to a 2D+1D effective gauge theory.
- Analysis of short-range (Thirring-like) and long-range interactions between surface states.
- Application of the large-N approximation in the strong-coupling limit.
Main Results:
- An excitonic gap is induced by the interaction between the two surface states.
- Dynamical mass generation for excitonic states occurs, preserving time-reversal symmetry.
- Chiral symmetry breaking is observed for fermion-flavor numbers below a critical value.
Conclusions:
- The inclusion of full dynamical interactions significantly modifies the critical flavor number for exciton condensation.
- Dynamical mass generation and chiral symmetry breaking are key features in this regime.
- Neglecting full dynamical interactions provides an incomplete picture of excitonic gap formation.
Related Concept Videos
01:22Semiconductors
1.7K
There is variation in the electrical conductivity of materials - metals, semiconductors, and insulators that are showcased with the help of the energy band diagrams.
Metals such as copper (Cu), zinc (Zn), or lead (Pb) have low resistivity and feature conduction bands that are either not fully occupied or overlap with the valence band, making a bandgap non-existent. This allows electrons in the highest energy levels of the valence band to easily transition to the conduction band upon gaining...
Metals such as copper (Cu), zinc (Zn), or lead (Pb) have low resistivity and feature conduction bands that are either not fully occupied or overlap with the valence band, making a bandgap non-existent. This allows electrons in the highest energy levels of the valence band to easily transition to the conduction band upon gaining...
1.7K
01:20Types of Semiconductors
1.6K
Intrinsic semiconductors are highly pure materials with no impurities. At absolute zero, these semiconductors behave as perfect insulators because all the valence electrons are bound, and the conduction band is empty, disallowing electrical conduction. The Fermi level is a concept used to describe the probability of occupancy of energy levels by electrons at thermal equilibrium. In intrinsic semiconductors, the Fermi level is positioned at the midpoint of the energy gap at absolute zero. When...
1.6K
01:27Electrostatic Boundary Conditions in Dielectrics
2.0K
When an electric field passes from one homogeneous medium to another, crossing the boundary between the two mediums imparts a discontinuity in the electric field. This results in electrostatic boundary conditions that depend on the type of mediums the field propagates through.
Consider a case where both the mediums across a boundary are two different dielectric materials. Recall that the electric field and electric displacement are proportional and related through the material's permittivity....
Consider a case where both the mediums across a boundary are two different dielectric materials. Recall that the electric field and electric displacement are proportional and related through the material's permittivity....
2.0K
01:26Imperfections in Crystal Structure: Stoichiometric Point Defects
14
Schottky defects arise when some lattice points in a crystal, such as those in NaCl, remain unoccupied, creating lattice vacancies without disturbing the overall electrical neutrality of the crystal. This defect is common in ionic crystals where the positive and negative ions are similar in size, as seen in sodium chloride and cesium chloride. The presence of Schottky defects enables the crystal to conduct electricity to a small extent through an ionic mechanism. Electric fields cause nearby...
14
02:35Band Theory
17.4K
When two or more atoms come together to form a molecule, their atomic orbitals combine and molecular orbitals of distinct energies result. In a solid, there are a large number of atoms, and therefore a large number of atomic orbitals that may be combined into molecular orbitals. These groups of molecular orbitals are so closely placed together to form continuous regions of energies, known as the bands.
The energy difference between these bands is known as the band gap.
Conductor, Semiconductor,...
The energy difference between these bands is known as the band gap.
Conductor, Semiconductor,...
17.4K
01:11P-N junction
1.5K
A p-n junction is formed when p-type and n-type semiconductor materials are joined together. At the interface of the p-n junction, holes from the p-side and electrons from the n-side begin to diffuse into the opposite sides due to the concentration gradient. This diffusion of carriers leads to a region around the junction where there are no free charge carriers, known as the depletion region. The charge density within the depletion region for the n-side and p-side can be described by the...
1.5K