[en] We report on high-excitation photoluminescence (PL) measurements of an ensemble of InAs/GaAs self-assembled quantum dots with large inter-shell spacing (75 meV) in magnetic fields up to 73 T. The PL spectra show a complex picture of levels splitting and crossings. A simple two-band single-particle model provides a good approximation to explain the observed magneto-PL spectra

[en] We studied the energy band structure of two-dimensional holes in p-type single Al_xGa_1-xAs/GaAs heterojunctions under a strong magnetic field up to 14 T. The electric field present in investigated structures near the interfaces produces a mixing of heavy and light hole states. This results in a strong nonparabolicity and anisotropy of energy levels and their non-linear behavior under an external magnetic field. We calculated energies and wave functions of hole subbands as a function of magnetic field in a Faraday configuration employing a realistic model of potential distribution and using new numerical method described in Kubisa et al., Phys. Rev. B 67 (2003) 035305. The theoretical results were compared with results of low-temperature photoluminescence measurements for samples with different 2D hole densities and a very good agreement was obtained

[en] We report on detailed investigations of low temperature (T=2 K) polarisation-resolved photoluminescence from heavily doped p-type Ga_1-xAl_xAs/GaAs single heterojunctions in magnetic field up to 23 T applied perpendicular to the structure. The unbound and the exciton bound transitions of photoexcited electrons with 2D holes were observed. The problem of free and localised charged exitons was discussed. The experimental data were compared with detailed numerical calculations

No abstract available

[en] Electronic properties of two-dimensional allotropes of carbon, such as graphene and its bilayer, multi-layer epitaxial graphene, few-layer Bernal-stacked graphene, as well as of three-dimensional bulk graphite are reviewed from the viewpoint of recent optical spectroscopy studies. Attention is focused on relativistic-like character of quasi-particles in these systems, which are referred to as massless or massive Dirac fermions. (topical review)

[en] The influence of intersubband mixing in quantum wells of semiconductors with zinc-blende structure is studied both experimentally and theoretically. A multiband magnetoexcitation model is described which takes into account k · p mixing between valence subbands and the effective Coulomb interaction for an arbitrary confinement potential shape. Theoretical results reproduce very well the photoluminescence excitation spectra of GaAs/AlGaAs single quantum wells of various widths. In particular, the characteristic avoided crossing between the lowest light-hole exciton Landau level and excited heavy-hole exciton Landau level occurring at σ^- polarization is accurately described by our theory. (author)

[en] Zeeman effect induced by the magnetic field introduces a splitting between the two valleys at K ⁺ and K ⁻ points of the Brillouin zone in monolayer semiconducting transition metal dichalcogenides. In consequence, the photoluminescence signal exhibits a field dependent degree of circular polarization. We present a comprehensive study of this effect in the case of a trion in monolayer MoTe₂, showing that although time integrated data allows us to deduce a g-factor of the trion state, such an analysis cannot be substantiated by the timescales revealed in the time-resolved experiments. (paper)

No abstract available

[en] Far-infrared magneto-transmission spectroscopy has been used to probe 'relativistic' fermions in highly oriented pyrolytic and natural graphite. Nearly identical transmission spectra of those two materials are obtained, giving the signature of Dirac fermions via absorption lines with an energy that scales as √B. The Fermi velocity is evaluated to be c-tilde=(1.02±0.02)x10⁶ m s^-1 and the pseudogap at the H point is estimated to |Δ|<10 meV.

No abstract available