نتایج جستجو برای: semimetals
تعداد نتایج: 1563 فیلتر نتایج به سال:
The excitonic insulator is a long conjectured correlated electron phase of narrow-gap semiconductors and semimetals, driven by weakly screened electron-hole interactions. Having been proposed more than 50 years ago, conclusive experimental evidence for its existence remains elusive. Ta2NiSe5 is a narrow-gap semiconductor with a small one-electron bandgap EG of <50 meV. Below TC=326 K, a putativ...
YPtBi, a topological semimetal with a very low carrier density, was recently found to be superconducting below T_{c}=0.77 K. In conventional theory, the nearly vanishing density of states around the Fermi level would imply a vanishing electron-phonon coupling and would, therefore, not allow for superconductivity. Based on relativistic density-functional theory calculations of the electron-phon...
Three-dimensional (3D) topological Dirac semimetal has a linear energy dispersion in 3D momentum space, and it can be viewed as an analogue of graphene. Extensive efforts have been devoted to the understanding of bulk materials, but yet it remains a challenge to explore the intriguing physics in low-dimensional Dirac semimetals. Here, we report on the synthesis of Cd3As2 nanowires and nanobelts...
In a type I Dirac or Weyl semimetal, the low-energy states are squeezed to a single point in momentum space when the chemical potential μ is tuned precisely to the Dirac/Weyl point. Recently, a type II Weyl semimetal was predicted to exist, where the Weyl states connect hole and electron bands, separated by an indirect gap. This leads to unusual energy states, where hole and electron pockets to...
Three-dimensional (3D) topological Dirac semimetals (TDSs) represent an unusual state of quantum matter that can be viewed as "3D graphene." In contrast to 2D Dirac fermions in graphene or on the surface of 3D topological insulators, TDSs possess 3D Dirac fermions in the bulk. By investigating the electronic structure of Na3Bi with angle-resolved photoemission spectroscopy, we detected 3D Dirac...
Weyl (WSMs) evolve from Dirac semimetals in the presence of broken time-reversal symmetry (TRS) or space-inversion symmetry. The WSM phases in TaAs-class materials and photonic crystals are due to the loss of space-inversion symmetry. For TRS-breaking WSMs, despite numerous theoretical and experimental efforts, few examples have been reported. In this Article, we report a new type of magnetic s...
For semimetals such as bismuth, ultrafast femtosecond laser-excited coherent phonons at laser fluences below the damage threshold have been studied extensively. In this work, we investigate whether or not coherent phonon oscillations contribute to material's permanent damage, or can enhance or suppress such damage. We employed temporally-shaped femtosecond pulses to either enhance or cancel coh...
We propose and characterize a new Z2 class of topological semimetals with a vanishing spin-orbit interaction. The proposed topological semimetals are characterized by the presence of bulk one-dimensional (1D) Dirac line nodes (DLNs) and two-dimensional (2D) nearly flat surface states, protected by inversion and time-reversal symmetries. We develop the Z2 invariants dictating the presence of DLN...
Abstract Weyl semimetals are topological materials whose electron quasiparticles obey the equation. They possess many unusual properties that may lead to new applications. This is a tutorial review of optical and applications semimetals. We basic concepts responses semimetals, survey their in optics thermal photonics. hope this pedagogical text will motivate further research on emerging topic.
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