A hallmark of graphene is its unusual conical band structure that leads to a zero-energy band gap at a single Dirac crossing point. By measuring the spectral function of charge carriers in quasi-freestanding graphene with angle-resolved photoemission spectroscopy, we showed that at finite doping, this well-known linear Dirac spectrum does not provide a full description of the charge-carrying ex...

We discuss the ultrafast evolution of the surface electronic structure of the topological insulator Bi(2)Te(3) following a femtosecond laser excitation. Using time and angle-resolved photoelectron spectroscopy, we provide a direct real-time visualization of the transient carrier population of both the surface states and the bulk conduction band. We find that the thermalization of the surface st...

A generalized relativistic harmonic oscillator for spin 1/2 particles is studied. The Dirac Hamiltonian contains a scalar S and a vector V quadratic potentials in the radial coordinate, as well as a tensor potential U linear in r. Setting either or both combinations S=S+V and D=V−S to zero, analytical solutions for bound states of the corresponding Dirac equations are found. The eigenenergies a...

The Dirac equation is not semisimple. We therefore construct it as a contraction of a simple theory. The underlying simple structure is necessarily purely algebraic and non-local. It consists of many isomorphic distinguishable qubits with Clifford-Wilczek statistics and spin h̄/2, having a Clifford algebra with 6N generators as algebra of observables. The quantum imaginary ih̄ arises as the vacuu...

Dienstag, 12. Januar 2016 17.15 Uhr Stuttgarter Physikalisches Kolloquium Max-Planck-Institut für Festkörperforschung Max-Planck-Institut für Intelligente Systeme Fachbereich Physik, Universität Stuttgart Hörsaal 2 D5 Stuttgarter Max-Planck-Institute, Heisenbergstraße 1, 70569 Stuttgart-Büsnau Ansprechpartner: Christian Ast E-Mail: [email protected] Telefon: 0711 689-5250 Topological crystalline...

Let X be a compact Kähler manifold with strictly pseudoconvex boundary, Y. In this setting, the SpinC Dirac operator is canonically identified with ∂̄ + ∂̄∗ : C∞(X ; Λ) → C∞(X ; Λ). We consider modifications of the classical ∂̄-Neumann conditions that define Fredholm problems for the SpinC Dirac operator. In part 2, [7], we use boundary layer methods to obtain subelliptic estimates for these bound...

A hierarchy of first-degree time-dependent symmetries is proposed for Dirac soliton hierarchy and their commutator relations with time-dependent symmetries are exhibited. Meantime, a hereditary structure of Dirac soliton hierarchy is elucidated and a Lax operator algebra associated with Virasoro symmetry algebra is given. The main purpose of the present letter is to construct a hierarchy of fir...

The conformal space M was introduced by Dirac in 1936. It is an algebraic manifold with a spin structure and possesses naturally an invariant Lorentz metric. By carefully studying the birational transformations of M, we obtain explicitly the transition functions of the spin bundle over M. Since the transition functions are closely related to the propagation in physics, we get a kind of solution...

The dynamical motion of mechanical systems possesses underlying geometric structures, and preserving these structures in numerical integration improves the qualitative accuracy and reduces the long-time error of the simulation. For a single mechanical system, structure preservation can be achieved by adopting the variational integrator construction. This construction has been generalized to mor...

We report electronic behavior of an allotrope of monolayer WS2 with a square octagon ring structure, refereed to as (so-WS2) within state-of-the-art density functional theory (DFT) calculations. TheWS2 monolayer shows semi-metallic characteristics with Dirac-cone like features around Г. Unlike p-orbital’s Dirac-cone in graphene, the Dirac-cone in the so-WS2 monolayer originates from the d-elect...