Sample interview questions: Can you explain the concept of topological semimetals and their potential applications in electronic devices?
Sample answer:
Topological semimetals (TSMs) are a class of materials that exhibit unique electronic properties due to their non-trivial band topology. They have attracted significant attention in recent years for their potential applications in electronic devices.
Concept of Topological Semimetals:
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Band Topology: In TSMs, the conduction and valence bands touch each other at specific points in the Brillouin zone, forming nodal points or lines. These nodal points are protected by topology, meaning they cannot be gapped out by continuous deformations of the material’s parameters.
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Dirac/Weyl Fermions: Near the nodal points, the electronic dispersion takes the form of a linear Dirac cone or a Weyl cone, respectively. The associated quasiparticles, known as Dirac or Weyl fermions, exhibit unique properties, such as high mobility, long mean free paths, and a chiral spin texture.
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Berry Curvature and Anomalous Hall Effect: TSMs possess a non-zero Berry curvature in momentum space, which gives rise to various topological phenomena. One notable effect is the anomalous Hall effect, which results in a transverse Hall voltage in the absence of an external magnetic field. This effect is highly tunable by external parameters like temperature, strain, and doping.
Potential Applications in Electronic Devices:
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High-Mobility Electronic Devices: The high mobility and long mean free paths of Dirac/Weyl fermions in TSMs make them promising candidates for high-speed electronic devices. They could potentially enable faster transistors and more efficient interconnects.
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Spintronics and Quantum Computing: The chiral spin texture of Dirac/Weyl fe… Read full answer
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