Related Experiment Video
Updated: Dec 15, 2025
10:42
Combining Solid-state and Solution-based Techniques: Synthesis and Reactivity of ChalcogenidoplumbatesII or IV
Published on: December 29, 2016
11.0K
Topologically Nontrivial Phase-Change Compound GeSb2Te4.
Munisa Nurmamat1,2, Kazuaki Okamoto1, Siyuan Zhu1
1Department of Physical Sciences, Graduate School of Science, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima 739-8526, Japan.
ACS Nano
|July 7, 2020
Summary
Researchers discovered that crystalline germanium antimony telluride (GeSb₂Te₄) exhibits topological properties, resembling a 3D graphene structure. This finding opens possibilities for creating novel, high-speed electronic devices utilizing inertia-free Dirac currents.
Area of Science:
- Condensed Matter Physics
- Materials Science
- Topological Materials
Background:
- Chalcogenide phase-change materials possess unique optical and electrical properties.
- These materials are widely used in memory device applications.
Purpose of the Study:
- To investigate the topological properties of crystalline germanium antimony telluride (GeSb₂Te₄).
- To explore the potential for realizing novel electronic phenomena in phase-change materials.
Main Methods:
- Spin-, time-, and angle-resolved photoemission spectroscopy (SPARPES).
- First-principles calculations.
- Experimental characterization of GeSb₂Te₄.
Main Results:
- The crystalline phase of GeSb₂Te₄ was identified as topologically nontrivial, near a Dirac semimetal phase.
- Linearly dispersive bulk Dirac-like bands crossing the Fermi level were observed.
- These bands are analogous to those in 3D graphene and responsible for conductivity.
Conclusions:
- GeSb₂Te₄ exhibits topological nontriviality, offering a platform for advanced electronic applications.
- The study demonstrates the potential for inertia-free Dirac currents in phase-change materials.
Related Concept Videos
02:31Phase Transitions
22.1K
Whether solid, liquid, or gas, a substance's state depends on the order and arrangement of its particles (atoms, molecules, or ions). Particles in the solid pack closely together, generally in a pattern. The particles vibrate about their fixed positions but do not move or squeeze past their neighbors. In liquids, although the particles are closely spaced, they are randomly arranged. The position of the particles are not fixed—that is, they are free to move past their neighbors to...
22.1K
02:46Crystal Field Theory - Tetrahedral and Square Planar Complexes
47.3K
Tetrahedral Complexes
Crystal field theory (CFT) is applicable to molecules in geometries other than octahedral. In octahedral complexes, the lobes of the dx2−y2 and dz2 orbitals point directly at the ligands. For tetrahedral complexes, the d orbitals remain in place, but with only four ligands located between the axes. None of the orbitals points directly at the tetrahedral ligands. However, the dx2−y2 and dz2 orbitals (along the Cartesian axes) overlap with the ligands less than the dxy,...
Crystal field theory (CFT) is applicable to molecules in geometries other than octahedral. In octahedral complexes, the lobes of the dx2−y2 and dz2 orbitals point directly at the ligands. For tetrahedral complexes, the d orbitals remain in place, but with only four ligands located between the axes. None of the orbitals points directly at the tetrahedral ligands. However, the dx2−y2 and dz2 orbitals (along the Cartesian axes) overlap with the ligands less than the dxy,...
47.3K
01:19Phase Diagram
6.8K
The phase of a given substance depends on the pressure and temperature. Thus, plots of pressure versus temperature showing the phase in each region provide considerable insights into the thermal properties of substances. Such plots are known as phase diagrams. For instance, in the phase diagram for water (Figure 1), the solid curve boundaries between the phases indicate phase transitions (i.e., temperatures and pressures at which the phases coexist).
6.8K
02:33Phase Transitions: Sublimation and Deposition
19.4K
Some solids can transition directly into the gaseous state, bypassing the liquid state, via a process known as sublimation. At room temperature and standard pressure, a piece of dry ice (solid CO2) sublimes, appearing to gradually disappear without ever forming any liquid. Snow and ice sublimate at temperatures below the melting point of water, a slow process that may be accelerated by winds and the reduced atmospheric pressures at high altitudes. When solid iodine is warmed, the solid sublimes...
19.4K
03:24Hybridization of Atomic Orbitals I
64.1K
The mathematical expression known as the wave function, ψ, contains information about each orbital and the wavelike properties of electrons in an isolated atom. When atoms are bound together in a molecule, the wave functions combine to produce new mathematical descriptions that have different shapes. This process of combining the wave functions for atomic orbitals is called hybridization and is mathematically accomplished by the linear combination of atomic orbitals. The new orbitals that...
64.1K
02:39Phase Diagrams
47.8K
A phase diagram combines plots of pressure versus temperature for the liquid-gas, solid-liquid, and solid-gas phase-transition equilibria of a substance. These diagrams indicate the physical states that exist under specific conditions of pressure and temperature and also provide the pressure dependence of the phase-transition temperatures (melting points, sublimation points, boiling points). Regions or areas labeled solid, liquid, and gas represent single phases, while lines or curves represent...
47.8K