Theory of Quantum Materials and Solid State Quantum Technologies, ICMM-CSIC

Group type: Theory

Research description: We investigate new properties of novel materials and nanostructures from a theoretical point of view: graphene, carbon nanotubes, nanowires, quantum dots and silicon nanoelectronics, topological insulators, superconductors and other strongly correlated systems. We describe materials and processes using model Hamiltonians, effective models, and ab-initio techniques. Both numerical and analytical approaches are used. While our approach is theoretical, we aim at understanding experimental data and making experimental predictions.

: Ratio of LDOS (in logarithmic color scale) at the top and bottom layers of a gated bilayer graphene with a grain boundary. Reference: Existence of nontrivial topologically protected states at grain boundaries in bilayer graphene: signatures and electrical switching, W. Jaskolski, M. Pelc, Leonor Chico, A. Ayuela, Nanoscale 8, 6079 (2016).

: Theory of Quantum Materials and Solid State Quantum Technologies, Materials Science Factory, ICMM-CSIC

: Schematic depiction of a graphene nanoribbon acting as a spin polarizer due to the Rashba effect induced by an external electric field. Reference: Symmetries of quantum transport with Rashba spin-orbit: graphene nanoelectronics, Leonor Chico, A. Latgé, L. Brey, Phys. Chem. Chem Phys. 17, 16469 (2015).

: Certain two-dimensional crystals, such as molybdenum disulphide (MoS2) and black phosphorus (BP) monolayers, have a bandgap that strongly depends on strains. In MoS2 it has been proposed to exploit this effect to funnel excitons (bound particle-hole pairs) using inhomogeneous strains, as those produced by a localized indenter. In BP the funnel effect is anisotropic and stronger than in MoS2, and crucially is of opposite sign. Such anisotropic inverse funnelling could be used e.g. to greatly enhance the performance of funnel solar cells.

: En la figura de la izquierda se puede ver cómo afecta la barrera a las funciones de onda de los estados fundamentales (light-hole y heavy-hole). En la fila superior el aceptor está a 7.5 nm de la intercara entre el silicio y la barrera aislante y mantiene en gran parte su simetría. En la fila inferior la distancia es de 1.5 nm y se puede ver cómo la intercara repele la función de onda, deformándola y reduciendo su simetría. En la figura de la derecha se puede ver cómo la separación de energía entre los estados fundamentales aumenta al reducirse la distancia del aceptor a la intercara. J.C Abadillo-Uriel, ICMM-CSIC

: Dynamical response of a graphene sample deposited on hexagonal boron nitride to a scanning nanoscopic tip (black circle). The color scale denotes the local in-plane strain induced by the moiré pattern produce by the lattice mismatch. As the scanning tip applies pressure locally, the strain field changes, strongly affecting the STM signal collected by the tip.