Related papers: Optical absorption in two-dimensional materials wi…
Physics arising from two-dimensional~(2D) Dirac cones has been a topic of great theoretical and experimental interest to studies of gapless topological phases and to simulations of relativistic systems. Such $2$D Dirac cones are often…
Type-II Dirac points (DPs), which occur at the intersection of strongly tilted and touching energy bands, exhibit many intriguing physical phenomena fundamentally different from the non-tilted type-I counterparts. Over the past decade,…
The type-II Weyl/Dirac fermions are a generalization of conventional or type-I Weyl/Dirac fermions, whose conic spectrum is tilted such that the Fermi surface becomes lines in two dimensions, and surface in three dimensions rather than…
We analyze the valley selection rules for optical transitions from impurity states to the conduction band in two-dimensional Dirac materials, taking a monolayer of MoS2 as an example. We employ the analytical model of a shallow impurity…
Topological semimetals have recently attracted extensive research interests as host materials to condensed matter physics counterparts of Dirac and Weyl fermions originally proposed in high energy physics. These fermions with linear…
Gated terahertz cyclotron resonance measurements on epitaxial Bi2Se3 thin films capped with In2Se3 enable the first spectroscopic characterization of a single topological interface state from the vicinity of the Dirac point to above the…
2D materials are well-known to exhibit interesting phenomena due to quantum confinement. Here, we show that quantum confinement, together with structural anisotropy, result in an electric-field-tunable Dirac cone in 2D black phosphorus.…
Type-II Dirac/Weyl semimetals are characterized by strongly tilted Dirac cones such that the Dirac/Weyl node emerges at the boundary of electron and hole pockets as a new state of quantum matter, distinct from the standard Dirac/Weyl points…
BaMg2Bi2 is a Dirac semimetal characterized by a simple Dirac cone crossing the Fermi level at the center of the Brillouin zone, protected by C3 rotational symmetry. Together with its Sr-based analogue SrMg2Bi2, it has been proposed as a…
TlBiSSe is a rare realization of a 3D semimetal with a conically dispersing band that has an optical response which is well isolated from other contributions in a broad range of photon eneries. We report optical and magneto-optical…
The over-tilting of Dirac cones has led to various fascinating quantum phenomena. Here we find that two anomalous acoustic plasmons (AAPs) are dictated by the distinct geometry of two-dimensional (2D) type-II Dirac cones, far beyond the…
We introduce the notion of a band-inverted, topological semimetal in two-dimensional nonsymmorphic crystals. This notion is materialized in the monolayers of MTe$_2$ (M $=$ W, Mo) if spin-orbit coupling is neglected. We characterize the…
The type-II Dirac cone is a special feature of the band structure, whose Fermi level is represented by a pair of crossing lines. It has been demonstrated that such a structure is useful for investigating topological edge solitons, and more…
Two-dimensional Dirac materials with a flat band have been demonstrated to possess a plethora of unusual electronic properties, but the optical properties of these materials are less studied. Utilizing $\alpha$-$\mathcal{T}_3$ lattice as a…
Superconductivity becomes more interesting when it encounters dimensional constraint or topology, because it is of importance for exploring exotic quantum phenomena or developing superconducting electronics. Here we report the coexistence…
The chiral optical absorption by a single vortex in a p_x \pm i p_y-wave superconductor is studied theoretically. The p_x \pm i p_y-wave state was recently suggested as the symmetry of the order parameter of Sr_2 Ru O_4 superconductor. Due…
The extraordinary electronic properties of Dirac materials, the two-dimensional partners of Weyl semimetals, arise from the linear crossings in their band structure. When the dispersion around the Dirac points is tilted, the emergence of…
The type-II Dirac fermions that are characterized by a tilted Dirac cone and anisotropic magneto-transport properties have been recently proposed theoretically and confirmed experimentally. Here, we predict the emergence of two-dimensional…
Here, we report by first-principles calculations one new stable 2D Dirac material, Ta2Se3 monolayer. For this system, stable layered bulk phase exists, and exfoliation should be possible. Ta2Se3 monolayer is demonstrated to support two…
Using an evolutionary algorithm in combination with first-principles density functional theory calculations, we identify two-dimensional (2D) CaP$_3$ monolayer as a new Dirac semimetal due to inversion and nonsymmorphic spatial symmetries…