The exotic electronic properties of topological semimetals (TSs) have opened new pathways for innovative photonic and optoelectronic devices, especially in the highly pursuit terahertz (THz) band. However, in most cases Dirac fermions lay far above or below the Fermi level, thus hindering their successful exploitation for the low-energy photonics. Here, low-energy type-II Dirac fermions in kitkaite (NiTeSe) for ultrasensitive THz detection through metal-topological semimetal-metal heterostructures are exploited. Furthermore, a heterostructure combining two Dirac materials, namely, graphene and NiTeSe, is implemented for a novel photodetector exhibiting a responsivity as high as 1.22 A W , with a response time of 0.6 µs, a noise-equivalent power of 18 pW Hz , with outstanding stability in the ambient conditions. This work brings to fruition of Dirac fermiology in THz technology, enabling self-powered, low-power, room-temperature, and ultrafast THz detection.
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http://dx.doi.org/10.1002/smll.202205329 | DOI Listing |
Nanomaterials (Basel)
December 2024
Department of Applied Mathematics, Waterloo Institute for Nanotechnology, University of Waterloo, Waterloo, ON N2L 3G1, Canada.
The aim of this study is to explore the potential which arises in a graphene-insulator-graphene structure when an external charged particle is moving parallel to it with a speed smaller than the Fermi speed in graphene. This is achieved by employing the dynamic polarization function of graphene within the random phase approximation, where its π electrons are modeled as Dirac fermions, and utilizing a local dielectric function for bulk insulators. Three different insulators are considered: SiO, HfO, and AlO.
View Article and Find Full Text PDFNat Commun
December 2024
Department of Physics, Key Laboratory of Quantum State Construction and Manipulation (Ministry of Education), and Beijing Key Laboratory of Opto-electronic Functional Materials & Micro-nano Devices, Renmin University of China, Beijing, 100872, China.
J Chem Phys
December 2024
Department of Chemistry, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA.
Several closely related ab initio thermal mean-field theories for fermions, both well-established and new ones, are compared with one another at the formalism level and numerically. The theories considered are Fermi-Dirac theory; thermal Hartree-Fock (HF) theory; two modifications of the thermal single-determinant approximation of Kaplan and Argyres, Ann. Phys.
View Article and Find Full Text PDFJ Phys Condens Matter
December 2024
Department of Physics, University of Allahabad, Prayagraj 211002, India.
The irradiation of topological insulator surface with elliptically polarized light modifies the topological properties in a phase-dependent manner impacting the Floquet Chern number which is a crucial topological invariant associated with such driven systems. Employing Floquet theory in presence of hexagonal warping term in the Dirac fermion Hamiltonian under off-resonant conditions, we derive an effective Hamiltonian that highlights distinct features in the Floquet-Dirac surface states. Specifically, we identify a helicity and ellipticity-dependent mass term in the quasi-static Hamiltonian, breaking time reversal symmetry.
View Article and Find Full Text PDFNano Lett
December 2024
Guangdong Provincial Key Laboratory of Magnetoelectric Physics and Devices, Center for Neutron Science and Technology, School of Physics, Sun Yat-Sen University, Guangzhou 510275, China.
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