Related Experiment Video
Updated: Jun 9, 2025
09:00
Experimental Methods for Spin- and Angle-Resolved Photoemission Spectroscopy Combined with Polarization-Variable Laser
Published on: June 28, 2018
9.9K
Visualization of spin-polarized surface resonances in Pb-based ternary topological insulators
Koichiro Yaji1,2, Yuya Hattori3, Shunsuke Yoshizawa3
1Center for Basic Research on Materials, National Institute for Materials Science (NIMS), 3-13, Sakura, Tsukuba, 305-0003, Ibaraki, Japan. yaji.koichiro@nims.go.jp.
Scientific Reports
|October 29, 2024
Summary
Researchers investigated Pb-based ternary topological insulators, Pb(Bi1-xSbx)2Te4, using advanced spectroscopy and calculations. They observed spin-polarized surface resonances that connect to the topological surface state, offering insights into topological phase transitions.
Area of Science:
- Condensed Matter Physics
- Materials Science
- Quantum Materials
Background:
- Topological surface states arise from bulk band inversion.
- Topological phase transitions mark the change between normal and topological insulators.
Purpose of the Study:
- To investigate spin-polarized electronic states in Pb-based ternary topological insulators, specifically Pb(Bi1-xSbx)2Te4.
- To explore the relationship between surface resonances and topological surface states in these materials.
Main Methods:
- Spin- and angle-resolved photoemission spectroscopy (SARPES)
- First-principles calculations
Main Results:
- Visualization of spin-polarized surface resonances in occupied states.
- Observation of a continuous connection between surface resonances and the topological surface state.
- Experimental and theoretical evidence for the coexistence of topological surface states and surface resonances.
Conclusions:
- The observed phenomena are explained by the concept of a topological phase transition.
- These findings contribute to understanding the electronic properties of topological insulators and their phase transitions.
Related Concept Videos
01:03Atomic Nuclei: Nuclear Spin State Overview
888
NMR-active nuclei have energy levels called 'spin states' that are associated with the orientations of their nuclear magnetic moments. In the absence of a magnetic field, the nuclear magnetic moments are randomly oriented, and the spin states are degenerate. When an external magnetic field is applied, the spin states have only 2 + 1 orientations available to them. A proton with = ½ has two available orientations. Similarly, for a quadrupolar nucleus with a nuclear spin value of...
888
02:42Valence Bond Theory
8.5K
Coordination compounds and complexes exhibit different colors, geometries, and magnetic behavior, depending on the metal atom/ion and ligands from which they are composed. In an attempt to explain the bonding and structure of coordination complexes, Linus Pauling proposed the valence bond theory, or VBT, using the concepts of hybridization and the overlapping of the atomic orbitals. According to VBT, the central metal atom or ion (Lewis acid) hybridizes to provide empty orbitals of suitable...
8.5K
03:02Colors and Magnetism
11.6K
Color in Coordination Complexes
When atoms or molecules absorb light at the proper frequency, their electrons are excited to higher-energy orbitals. For many main group atoms and molecules, the absorbed photons are in the ultraviolet range of the electromagnetic spectrum, which cannot be detected by the human eye. For coordination compounds, the energy difference between the d orbitals often allows photons in the visible range to be absorbed and emitted, which is seen as colors by the human...
When atoms or molecules absorb light at the proper frequency, their electrons are excited to higher-energy orbitals. For many main group atoms and molecules, the absorbed photons are in the ultraviolet range of the electromagnetic spectrum, which cannot be detected by the human eye. For coordination compounds, the energy difference between the d orbitals often allows photons in the visible range to be absorbed and emitted, which is seen as colors by the human...
11.6K
01:22Spin–Spin Coupling: Three-Bond Coupling (Vicinal Coupling)
1.0K
Vicinal or three-bond coupling is commonly observed between protons attached to adjacent carbons. Here, nuclear spin information is primarily transferred via electron spin interactions between adjacent C‑H bond orbitals. This generally favors the antiparallel arrangement of spins, so 3J values are usually positive.
The extent of coupling depends on the C‑C bond length, the two H‑C‑C angles, any electron-withdrawing substituents, and the dihedral angle between the...
The extent of coupling depends on the C‑C bond length, the two H‑C‑C angles, any electron-withdrawing substituents, and the dihedral angle between the...
1.0K
01:08NMR Spectroscopy: Spin–Spin Coupling
1.3K
The spin state of an NMR-active nucleus can have a slight effect on its immediate electronic environment. This effect propagates through the intervening bonds and affects the electronic environments of NMR-active nuclei up to three bonds away; occasionally, even farther. This phenomenon is called spin–spin coupling or J-coupling. Coupling interactions are mutual and result in small changes in the absorption frequencies of both nuclei involved. While nuclei of the same element are involved...
1.3K
01:17Spin–Spin Coupling: One-Bond Coupling
949
Coupling interactions are strongest between NMR-active nuclei bonded to each other, where spin information can be transmitted directly through the pair of bonding electrons. While nuclei polarize their electrons to the opposite spins, the bonding electron pair has opposite spins. Configurations with antiparallel nuclear spins are expected to be lower in energy. When coupling makes antiparallel states more favorable, J is considered to have a positive value. The one-bond coupling constant, 1J,...
949