RESUMEN
Combining multiple emergent correlated properties such as superconductivity and magnetism within the topological matrix can have exceptional consequences in garnering new and exotic physics. Here, we study the topological surface states from a noncentrosymmetric α-BiPd superconductor by employing angle-resolved photoemission spectroscopy and first-principles calculations. We observe that the Dirac surface states of this system have several interesting and unusual properties, compared to other topological surface states. The surface state is strongly anisotropic and the in-plane Fermi velocity varies rigorously on rotating the crystal about the y axis. Moreover, it acquires an unusual band gap as a function of k_{y}, possibly due to hybridization with bulk bands, detected upon varying the excitation energy. The coexistence of all the functional properties in addition to the unusual surface state characteristics make this an interesting material.
RESUMEN
The electronic and optical properties of zincblende nanowires are investigated in the presence of a uniform magnetic field directed along the [001] growth direction within the k · p method. We focus our numerical study on core-shell nanowires consisting of the III-V materials GaAs, Al(x)Ga(1-x)As and (Al(y)Ga(1-y))0.51In0.49P. Nanowires with electrons confined in the core exhibit a Fock-Darwin-like spectrum, whereas nanowires with electrons confined in the shell show Aharonov-Bohm oscillations. Thus, by properly choosing the core and the shell materials of the nanowire, the optical properties in a magnetic field can be tuned in very different ways.
RESUMEN
The electronic structure of GaAs, InAs and InSb nanowires is studied using the six-band and the eight-band k·p models. The effect of the different Luttinger-like parameters (in the eight-band model) on the hole band structure is investigated. Although GaAs nanostructures are often treated within a six-band model because of the large bandgap, it is shown that an eight-band model is necessary for a correct description of its hole spectrum. The camel-back structure usually found in the six-band model is not always present in the eight-band model. This camel-back structure depends on the interaction between light and heavy holes, especially the ones with opposite spin. The latter effect is less pronounced in an eight-band model, but could be very sensitive to the Kane inter-band energy (E(P)) value.
