Related Experiment Video
Updated: Jul 10, 2025

Experimental Methods for Spin- and Angle-Resolved Photoemission Spectroscopy Combined with Polarization-Variable Laser
Published on: June 28, 2018
Antiferromagnetic topological insulator with selectively gapped Dirac cones
A Honma1, D Takane1, S Souma2,3
1Department of Physics, Graduate School of Science, Tohoku University, Sendai, 980-8578, Japan.
Researchers discovered the antiferromagnetic (AF) topological-insulator phase in NdBi. This finding links electronic states and topology in AF materials, enabling new quantum phenomena exploration.
Area of Science:
- Condensed Matter Physics
- Materials Science
- Quantum Phenomena
Background:
- Antiferromagnetic (AF) topological materials are promising for exploring quantum phenomena like axion magnetoelectric dynamics.
- Establishing a link between electronic states and topology in the AF phase is crucial but challenging due to a lack of suitable materials.
Purpose of the Study:
- To experimentally realize the AF topological-insulator phase.
- To investigate the relationship between electronic states and topology in AF materials.
Main Methods:
- Micro-focused angle-resolved photoemission spectroscopy (μ-ARPES).
- Characterization of surface electronic states in NdBi.
Main Results:
- Experimental realization of the AF topological-insulator phase in NdBi.
- Observed contrasting surface electronic states for different AF domains.
- Discovery of gapped Dirac-cone states on surfaces with out-of-plane AF ordering.
- Identification of gapless Dirac states on surfaces parallel to the AF ordering vector, despite time-reversal symmetry breaking.
Conclusions:
- NdBi serves as a platform for AF topological-insulator research.
- Combined symmetry plays a key role in protecting massless Dirac fermions in AF materials.
- This work opens avenues for exotic phenomena in AF topological materials.
More Related Videos
09:06Visualizing Uniaxial-strain Manipulation of Antiferromagnetic Domains in Fe1+YTe Using a Spin-polarized Scanning Tunneling Microscope
Published on: March 24, 2019
05:39Scalable Quantum Integrated Circuits on Superconducting Two-Dimensional Electron Gas Platform
Published on: August 2, 2019
Related Concept Videos
Semiconductors
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...
Fermi Level
At absolute zero temperature, electrons fill all energy states up to the Fermi level, leaving upper states empty. As the temperature rises,...
Band Theory
The energy difference between these bands is known as the band gap.
Conductor, Semiconductor,...
Ferromagnetism
Valence Bond Theory
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,...