Related Experiment Video
Updated: May 29, 2026
09:00
Experimental Methods for Spin- and Angle-Resolved Photoemission Spectroscopy Combined with Polarization-Variable Laser
Published on: June 28, 2018
Torsional response and dissipationless viscosity in topological insulators
Taylor L Hughes1, Robert G Leigh, Eduardo Fradkin
1Department of Physics, University of Illinois, Urbana, 61801, USA.
Physical Review Letters
|September 10, 2011
Summary
Topological insulators exhibit unique dissipationless viscosity due to lattice geometry changes. This quantum Hall viscosity in 2D Chern insulators extends to 3D topological insulators surfaces.
Area of Science:
- Condensed matter physics
- Materials science
Background:
- Topological insulators (TI's) possess unique electronic properties.
- Quantum Hall states exhibit quantized viscosity.
Purpose of the Study:
- Investigate the viscoelastic response of electronic degrees of freedom in 2D and 3D TI's.
- Characterize the bulk dissipationless viscosity in 2D Chern insulators.
Main Methods:
- Theoretical analysis of electronic response to lattice deformations.
- Exploration of topological properties and quantum viscosity.
Main Results:
- Identified a bulk dissipationless viscosity in 2D Chern insulators, analogous to quantum Hall viscosity.
- Demonstrated that this viscosity arises from torsional deformations of the lattice.
- Showed that crystal dislocations in Chern insulators carry momentum density.
- Extended findings to 3D TI's, predicting surface quantum Hall viscosity.
Conclusions:
- 2D Chern insulators exhibit novel viscoelastic behavior linked to geometric effects.
- The study provides a framework for understanding topological quantum viscosity in condensed matter systems.
Related Concept Videos
01:17Theory of Metallic Conduction
The conduction of free electrons inside a conductor is best described by quantum mechanics. However, a classical model makes predictions close to the results of quantum mechanics. It is called the theory of metallic conduction.
In this theory, Newton's second law of motion is used to determine the acceleration of an electron in the presence of an applied electric field. Then, its velocity is expressed via this acceleration.
An electron moves through the crystal, containing positive ions,...
In this theory, Newton's second law of motion is used to determine the acceleration of an electron in the presence of an applied electric field. Then, its velocity is expressed via this acceleration.
An electron moves through the crystal, containing positive ions,...
01:15Thin-Walled Hollow Shafts
In analyzing a thin-walled hollow shaft subjected to torsional loading, a segment with width dx is isolated for examination. Despite its equilibrium state, this segment faces torsional shearing forces at its ends. These forces are quantitatively described by the product of the longitudinal shearing stress on the segment's minor surface and the area of this surface, leading to the concept of shear flow. This shear flow is consistent throughout the structure, indicating a uniform distribution of...
01:17Gauss's Law in Dielectrics
Consider a polar dielectric placed in an external field. In such a dielectric, opposite charges on adjacent dipoles neutralize each other, such that the net charge within the dielectric is zero. When a polar dielectric is inserted in between the capacitor plates, an electric field is generated due to the presence of net charges near the edge of the dielectric and the metal plates interface. Since the external electrical field merely aligns the dipoles, the dielectric as a whole is neutral. An...
01:19Viscosity of Fluid
Viscosity measures the resistance a fluid offers to flow and deformation. It results from internal friction between layers of fluid moving relative to one another. Dynamic viscosity, denoted by the Greek letter mu (μ), quantifies the force needed to move one fluid layer over another. For Newtonian fluids like water and air, the relationship between the shearing stress and the rate of shearing strain is linear, meaning their viscosity remains constant regardless of the applied stress.
01:11Rotation of Asymmetric Top
By definition, a spherically symmetric body has the same moment of inertia about any axis passing through its center of mass. This situation changes if there is no spherical symmetry. Since most rigid bodies are not spherically symmetric, these require special treatment.
The relationship between the angular momentum of any rigid body and its angular velocity, both of which are vectors, involves the moment of inertia. The moment of inertia is a scalar quantity only for spherically symmetric...
The relationship between the angular momentum of any rigid body and its angular velocity, both of which are vectors, involves the moment of inertia. The moment of inertia is a scalar quantity only for spherically symmetric...
01:27Electrostatic Boundary Conditions in Dielectrics
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.