1,085 research outputs found
Interactions and superconductivity in heavily doped MoS2
We analyze the microscopic origin and the physical properties of the
superconducting phase recently observed in MoS. We show how the combination
of the valley structure of the conduction band, the density dependence of the
screening of the long range Coulomb interactions, the short range electronic
repulsion, and the relative weakness of the electron-phonon interactions, makes
possible the existence of a phase where the superconducting order parameter has
opposite signs in different valleys, resembling the superconductivity found in
the pnictides and cuprates
Midgap states and charge inhomogeneities in corrugated graphene
We study the changes induced by the effective gauge field due to ripples on
the low energy electronic structure of graphene. We show that zero energy
Landau levels will form, associated to the smooth deformation of the graphene
layer, when the height corrugation, , and the length of the ripple, , are
such that , where is the lattice constant. The
existence of localized levels gives rise to a large compressibility at zero
energy, and to the enhancement of instabilities arising from electron-electron
interactions including electronic phase separation. The combined effect of the
ripples and an external magnetic field breaks the valley symmetry of graphene
leading to the possibility of valley selection
Dynamics of Holes and Universality Class of the Antiferromagnetic Transition in the Two Dimensional Hubbard Model
The dynamics of a single hole (or electron) in the two dimensional Hubbard
model is investigated. The antiferromagnetic background is described by a
N\`eel state, and the hopping of the carrier is analyzed within a configuration
interaction approach. Results are in agreement with other methods and with
experimental data when available. All data are compatible with the opening of a
mean field gap in a Fermi liquid of spin polarons, the so called Slater type of
transition. In particular, this hypothesis explains the unusual dispersion
relation of the quasiparticle bands near the transition. Recent photoemission
data for CaCuOCl are analyzed within this context.Comment: New results and comparison with recent data adde
Strain-induced bound states in transition-metal dichalcogenide bubbles
This is an author-created, un-copyedited version of an article published in 2D Materials. IOP Publishing Ltd is not responsible for any errors or omissions in this version of the manuscript or any version derived from it. The Version of Record is available online at https://doi.org/10.1088/2053-1583/ab0113We theoretically study the formation of single-particle bound states confined by strain at the center of bubbles in monolayers of transition-metal dichalcogenides (TMDs). Bubbles ubiquitously form in two-dimensional crystals on top of a substrate by the competition between van der Waals forces and the hydrostatic pressure exerted by trapped fluid. This leads to strong strain at the center of the bubble that reduces the bangap locally, creating potential wells for the electrons that confine states inside. We simulate the spectrum versus the bubble radius for the four semiconducting group VI TMDs, MoS2, WSe2, WS2 and MoSe2, and find an overall Fock-Darwin spectrum of bubble bound states, characterised by small deviations compatible with Berry curvature effects. We analyse the density of states, the state degeneracies, orbital structure and optical transition rules. Our results show that elastic bubbles in these materials are remarkably efficient at confining photocarriersWe acknowledge funding from the Graphene Flagship, contract CNECTICT-604391, from the Comunidad de Madrid through Grant MAD2D-CM, S2013/MIT-3007, from the Spanish Ministry of Economy and Competitiveness through Grants No. RYC-2011-09345, RYC-2016-20663, FIS2015-65706-P, FIS2016-80434-P (AEI/FEDER, EU) and the MarÃa de Maeztu Programme for Units of Excellence in R&D (MDM-2014-0377
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