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Through this ICMM space slack account you will be able to navigate the funk, padel, soccer, dance, articles-icmm, scientic-questions channel and many other things such as helping the new icmm-nautas. You can also open your own #channel to find people who share your interests. Join us! Read more

About

The Instituto de Ciencia de Materiales de Madrid (ICMM) is an institute of the Consejo Superior de Investigaciones Cientificas (CSIC) (Spanish National Research Council) founded in December 1986, that belongs to the Area of Science and Technology of Materials, one of the eight Areas in which the CSIC divides its research activities.

 

Our mission is to create new fundamental and applied knowledge in materials of high technological impact, their processing and their transfer to the productive sectors at local, national and European scales (the true value of materials is in their use), the training of new professionals, and the dissemination of the scientific knowledge.

How to arrive

Forthcoming Events

APR25/12:00

Thermoelectric graphene nanostructures
Francisco Domínguez-Adame  read more

APR29/12:00

Novel Applications of High Frequency Radiations:
I) THz Radiation and Art, a New Tool in the Inspection of Cultural Heritage. II) Potential Use of GHz Radiation in Medicine

Javier Tejada Palacios  read more

MAY06/12:00

Internal screening and dielectric engineering in magic-angle twisted bilayer graphene
J. M. Pizarro  read more

Kohn-Luttinger Superconductivity in Twisted Bilayer Graphene

J. González and T. Stauber

We show that the recently observed superconductivity in twisted bilayer graphene (TBG) can be explained as a consequence of the Kohn-Luttinger (KL) instability which leads to an effective attraction between electrons with originally repulsive interaction. Usually, the KL instability takes place at extremely low energy scales, but in TBG, a doubling and subsequent strong coupling of the van Hove singularities (vHS) in the electronic spectrum occurs as the magic angle is approached, leading to extended saddle points in the highest valence band with almost perfect nesting between states belonging to different valleys. The highly anisotropic screening induces an effective attraction in a p-wave channel with odd parity under the exchange of the two disjoined patches of the Fermi line. We also predict the appearance of a spin-density wave instability, adjacent to the superconducting phase, and the opening of a gap in the electronic spectrum from the condensation of spins with wave vector corresponding to the nesting vector close to the vHS.

Phys. Rev. Lett. 2019

(a) and (b) Density plot of the energy dispersion of the highest valence band E+k=max(EKk,EKk) in the moiré Brillouin zone of the continuous model for two different twist angles. Dark (bright) colors represent high (low) energies and the black contour lines represent the Fermi surface at the energy of the van Hove singularity EvH. There occurs a doubling of the vHS at some critical angle θi=24>θ+c>θi=25, i.e., for lower θ there are twelve saddle points located inside the MBZ close to the lines that connect the Γ and K points. (c) and (d) Contour plot of the highest valence bands E+k and Ek of the tight-binding model for i=26. The two sets of vHS belonging to different valleys have already merged and are found now in different bands E+k and Ek.

ICMM-2019 - Sor Juana Inés de la Cruz, 3, Cantoblanco, 28049 Madrid, Spain. Tel: +34 91 334 9000. info@icmm.csic.es