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.
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CANCELADO - Nanofabrications and its applications at Fudan University in China Yifang Chen read more
Líquidos Iónicos en Tribología e Ingeniería de Superficies María Dolores Bermúdez Olivares read more
Electrically controllable magnetism in twisted bilayer graphene
Luis A. Gonzalez-Arraga, J. L. Lado, Francisco Guinea and Pablo San-Jose
Twisted graphene bilayers develop highly localised states around AA-stacked regions for small twist angles. We show that interaction effects may induce either an antiferromagnetic (AF) and a ferromagnetic (F) polarization of said regions, depending on the electrical bias between layers. Remarkably, F-polarised AA regions under bias develop spiral magnetic ordering, with a relative 120o misalignment between neighbouring regions due to a frustrated antiferromagnetic exchange. This remarkable spiral magnetism emerges naturally without the need of spin-orbit coupling, and competes with the more conventional lattice-antiferromagnetic instability, which interestingly develops at smaller bias under weaker interactions than in monolayer graphene, due to Fermi velocity suppression. This rich and electrically controllable magnetism could turn twisted bilayer graphene into an ideal system to study frustrated magnetism in two dimensions, with interesting potential also for a range of applications.
Zero-energy local density of states in real space (a,b),
bandstructure (c,d) and density of states (e,f) for a θ = 1.5
twisted graphene bilayer. The left column has no interlayer
bias, and the right column has a bias Vb = 300 meV. This
enhances the localization of the AA quasibound states, red
in (a,b). Said states arise from almost flat subbands at zero
energy, which show up as large DOS peaks in (e,f). Solid
(dashed) lines in (c,d) correspond to a scaled (unscaled) tightbinding
model, see main text.