相关论文: Single valley Dirac fermions in zero-gap HgTe quan…
A key problem in the field of quantum criticality is to understand the nature of quantum phase transitions in systems of interacting itinerant fermions, motivated by experiments on a variety of strongly correlated materials. Much attention…
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 material termed three-dimensional (3D) Dirac semimetal has attracted great interests recently, since it is an electronic analogue to two-dimensional graphene. Starting from this novel phase, various topologically distinct phases may be…
Spin-orbit coupling in thin HgTe quantum wells results in a relativistic-like electron band structure, making it a versatile solid state platform to observe and control non-trivial electrodynamic phenomena. Here we report an observation of…
Looking for new materials with Dirac points has been a fascinating subject of research. Here we report the growth, crystal structure, and band structure of HfGe0.92Te single crystals, featuring three different types of Dirac points.…
We discuss the surface magnetotransport in the quantum Hall (QH) ferromagnetic state expected in the organic Dirac fermion system \alpha-(BEDT-TTF)_2I_3. The QH ferromagnetic state is one of the possible \nu=0 QH states in the…
We use Pseudo Quantum Electrodynamics to study massive (2+1)D Dirac systems interacting electromagnetically via a U(1) gauge field in (3+1)D. It was recently found in Ref. [1], that an interaction-induced Quantum Hall Effect (QHE) and…
Topological band dispersions other than the standard Dirac or Weyl fermions have garnered the increasing interest in materials science. Among them, the cubic Dirac fermions were recently proposed in the family of quasi-one-dimensional…
The electronic state of \alpha-type organic Dirac fermion systems such as \alpha-(ET)_2I_3 or \alpha-(BETS)_2I_3 has been studied under magnetic fields using the four-band tight-binding model with Peierls phase factors. The validity of the…
Spin-valley locking in the band structure of monolayers of MoS$_2$ and other group-VI dichalcogenides has attracted enormous interest, since it offers potential for valleytronic and optoelectronic applications. Such an exotic electronic…
Dirac electrons in a single-component molecular conductor [Pd(dddt)$_2$] under pressure have been examined using a tight-binding model which consists of HOMO (Highest Occupied Molecular Orbital) and LUMO (Lowest Unoccupied Molecular…
The energies as a function of the magnetic field ($H$) and the pressure are studied theoretically in the tight-binding model for the two-dimensional organic conductor, $\alpha$-(BEDT-TTF)$_2$I$_3$, in which massless Dirac fermions are…
Two-dimensional electrons in graphene are known to behave as massless fermions with Dirac-Weyl type linear dispersion near the Dirac crossing points. We have investigated the collective excitations of this system in the presence or absence…
Large-gap quantum spin Hall insulators are promising materials for room-temperature applications based on Dirac fermions. Key to engineer the topologically non-trivial band ordering and sizable band gaps is strong spin-orbit interaction.…
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…
The robustness of quantum edge transport in InAs/GaSb quantum wells in the presence of magnetic fields raises an issue on the fate of topological phases of matter under time-reversal symmetry breaking. A peculiar band structure evolution in…
Landau level bending near the edge of graphene, described using 2d Dirac equation, provides a microscopic framework for understanding the quantum Hall Effect (QHE) in this material. We review properties of the QHE edge states in graphene,…
The quantum Hall effect (QHE), which was observed in 2D electron gas under an external magnetic field, stands out as one of the most remarkable transport phenomena in condensed matter. However, a long standing puzzle remains regarding the…
While electron-electron (e-e) interactions are known to influence resistivity in non-Galilean invariant two-dimensional (2D) systems, their effect on magnetotransport is not fully understood. Conventional models for simple bands often…
Realizations of some topological phases in two-dimensional systems rely on the challenge of jointly incorporating spin-orbit and magnetic exchange interactions. Here, we predict the formation and control of a fully valley-polarized quantum…