Ikerbasque

About: Ikerbasque is a other organization based out in Bilbao, Spain. It is known for research contribution in the topics: Graphene & Quantum. The organization has 713 authors who have published 7967 publications receiving 231990 citations. The organization is also known as: Basque Foundation for Science.

Change of the Magnetic Coupling of a Metal–Organic Complex with the Substrate by a Stepwise Ligand Reaction

Abstract: The surface-assisted intramolecular ligand reaction of a porphyrin molecule adsorbed on Au(111) is studied by scanning tunneling microscopy and spectroscopy. The temperature-induced stepwise transformation of iron octaethylporphyrin proceeds via a concentric electrocyclic ring closure, with the final product iron tetrabenzoporphyrin being identified by its characteristic Kondo resonance. Along with the transformation of the organic ligand, changes in the magnetic fingerprint are observed, indicating an increasing coupling of the iron spin with the substrate electrons.

Terahertz Nanofocusing with Cantilevered Terahertz-Resonant Antenna Tips

Abstract: We developed THz-resonant scanning probe tips, yielding strongly enhanced and nanoscale confined THz near fields at their tip apex. The tips with length in the order of the THz wavelength (λ = 96.5 μm) were fabricated by focused ion beam (FIB) machining and attached to standard atomic force microscopy (AFM) cantilevers. Measurements of the near-field intensity at the very tip apex (25 nm radius) as a function of tip length, via graphene-based (thermoelectric) near-field detection, indicate their first and second order geometrical antenna resonances for tip length of 33 and 78 μm, respectively. On resonance, we find that the near-field intensity is enhanced by one order of magnitude compared to tips of 17 μm length (standard AFM tip length), which is corroborated by numerical simulations that further predict remarkable intensity enhancements of about 107 relative to the incident field. Because of the strong field enhancement and standard AFM operation of our tips, we envision manifold and straightforward f...

Giant topological longitudinal circular photo-galvanic effect in the chiral multifold semimetal CoSi

Abstract: The absence of mirror symmetry, or chirality, is behind striking natural phenomena found in systems as diverse as DNA and crystalline solids A remarkable example occurs when chiral semimetals with topologically protected band degeneracies are illuminated with circularly polarized light Under the right conditions, the part of the generated photocurrent that switches sign upon reversal of the light's polarization, known as the circular photogalvanic effect, is predicted to depend only on fundamental constants The conditions to observe quantization are non-universal, and depend on material parameters and the incident frequency In this work, we perform terahertz emission spectroscopy with tunable photon energy from 02 eV - 11 eV in the chiral topological semimetal CoSi We identify a large longitudinal photocurrent peaked at 04 eV reaching $\sim$ 550 $\mu A/V^{2}$, which is much larger than the photocurrent in any chiral crystal reported in the literature Using first-principles calculations we establish that the peak originates from topological band crossings, reaching 33$\pm$03 in units of the quantization constant Our calculations indicate that the quantized CPGE is within reach in CoSi upon doping and increase of the hot-carrier lifetime The large photo-conductivity suggests that topological semimetals could potentially be used as novel mid-infrared detectors

Dis&approval voting: a characterization

Abstract: The voting rule considered in this paper belongs to a large class of voting systems, called “range voting” or “utilitarian voting”, where each voter rates each candidate with the help of a given evaluation scale and the winner is the candidate with the highest total score. In approval voting the evaluation scale only consists of two levels: 1 (approval) and 0 (non approval). However non approval may mean disapproval or just indifference or even absence of sufficient knowledge for evaluating the candidate. In this paper we propose a characterization of a rule (that we refer to as dis&approval voting) that allows for a third level in the evaluation scale. The three levels have the following interpretation: 1 means approval, 0 means indifference, abstention or ‘do not know’, and \(-1\) means disapproval.