Donostia International Physics Center

CeTe3 is a 2-dimensional (2D) Van der Waals (VdW) material with incommensurate charge density waves (CDW), extremely high transition temperature (TCDW), and a large momentum-dependent CDW gap that leaves a significant portion of the Fermi surface intact. It is also considered to be a weak Kondo system, a property unexpected for a material with incommensurate CDW, where each atomic site is slightly different. Here, we study the properties of the CDW state in several RTe3 (R is rare earth) materials and examine the hybridization of itinerant states with the localized Ce 4f multiplet in CeTe3 by using angle resolved photoemission spectroscopy. We find that the renormalization of the itinerant states originating from the hybridization with the deeper localized 4f states at −260 meV is k−dependent and extends to the Fermi level. As these localized states are far from the Fermi level, the observed hybridization affects the effective masses only marginally and does not lead to heavy fermions. However, since the same renormalizing mechanism normally leads to the heavy fermion physics when the localized 4f states are near the Fermi level, our observation of its strong k−dependence suggests that this could be the reason for discrepancy between the heavy masses in specific heat and light ones in Shubnikov de Haas oscillations, often observed in heavy fermions.

Polymorphism in polyarenes significantly impacts their applications, yet remains underexplored in curved species like corannulene. To this end, we utilised fast scanning calorimetry and X-ray diffraction to explore its stability regimes. Unlike its flat counterpart perylene, corannulene exhibits a glass transition at Tg=323 K when cooled from the melt at rates exceeding -500 K s-1. Upon heating, three thermal events at ca. 380, 430, and 500 K reveal hitherto unknown polymorphs. Diffraction data link these transitions to well-defined and thermally activated rotations within the crystal, inducing a sharp density decrease matching Tg. These changes are accompanied by abnormal atomic displacement parameters. Unlike flat polyarenes of a similar molecular size, the diffraction data also provide strong evidence that this solid ought to be regarded as two distinctly different materials below and above Tg. Altogether, our findings bring to the fore the unanticipated complexity underpinning the structure and thermodynamic response of solid corannulene, the simplest geodesic polyarene.

ABSTRACT Polaritonic crystals for hyperbolic phonon‐polaritons (PhP) in van der Waals materials are burdened by the intermode scattering due to the inherently multimodal nature of PhP. So far, polaritonic crystals have been demonstrated within the Type‐II Reststrahlen band (RB‐II) where the in‐plane components of the dielectric permittivity tensor are negative, while the out‐of‐plane component is positive. By contrast, a Type‐I Reststrahlen band (RB‐I) is characterized by the negative out‐of‐plane and positive in‐plane permittivity, and consequently, the inversion of PhP field symmetry, negative phase velocity, and anomalous dispersion. Such an operation regime remains unexplored for periodic structures supporting collective polaritonic modes. Here, we employ a biaxial crystal α‐MoO 3 and near‐field imaging to study mid‐infrared polaritonic Bloch modes in a 1‐D Fourier crystal within the RB‐I. Surprisingly, we observe a manifestation of Bloch waves as a dispersionless near‐field pattern across the first Brillouin zone, in contrast to previous works exclusively focused on the RB‐II. Our results demonstrate the possibility to realize a quasi‐single‐mode operation regime of polaritonic crystal for the inherently multimode hyperbolic PhP, and reveal the importance of field symmetry for polaritonic crystals in general and for the emerging field of Fourier crystals in particular, promising new ways to manipulate the nanolight.

ABSTRACT The enigmatic Little Red Dots (LRDs) discovered by the James Webb Space Telescope (JWST) exhibit properties challenging their interpretation as common galaxies or active galactic nuclei (AGNs). Understanding their nature is key to placing them within our picture of early galaxy and massive black hole (MBH) evolution. To this aim, we build a realistic comparison between LRD observations with photometric properties of galaxies and AGN simulated by the L-GalaxiesBH model in a NIRCam mock sky. We model stellar continua and emission lines, the MBH emission from accretion disc, infrared radiation from dusty torus, and lines from narrow and broad-line regions, accounting for dust attenuation and obscuration. Using realistic photometric cuts, we select a population of LRDs including both AGN and galaxies. The LRD fraction peaks at 40 per cent ($\sim 10^{-4}\rm Mpc^{-3}$) at $z\sim 4$. Our LRDs are central galaxies spanning $M_\star =10^8{\!-\!}10^{10.5}\rm M_\odot$. A population of galaxies with $M_\star \lt 10^9\rm M_\odot$ appear as LRDs due to older stellar populations. At higher masses, LRDs dominate the halo and stellar mass functions ($M_{\rm vir} \gt 10^{11.5}\rm M_\odot$, $M_\star \gt 10^{9.5}\rm M_\odot$), and the interplay between AGN and galaxy emission drives the LRD selection. AGN dominate rest-frame UV-optical emission, while dust obscuration is secondary. LRDs host lighter MBHs ($\sim 10^{6.5}\rm M_\odot$) than non-LRDs ($\sim 10^{7.5}\rm M_\odot$), with fainter emission unable to balance their hosts Balmer breaks. We find no evidence for dominant heavy-seed origin of MBHs. LRD Galaxies (97 per cent hosting MBHs) and LRD AGNs are disc-dominated, with LRD AGNs showing larger bulges formed mainly via disc instabilities.

Chirality-Induced Skyrmion Crystals Chirality emerges as a key driver of skyrmion lattice organization and functionality. In CrBr3, a weak in-plane magnetic field induces spontaneous chirality switching, reshaping skyrmions and triggering their crystallisation from a disordered liquid into an ordered hexatic lattice. This chirality-driven ordering highlights new opportunities for robust, low-energy information storage and reconfigurable chiral spintronic devices. More details can be found in the Research Article by John Fullerton, Yue Li, Elton J. G. Santos, Charudatta Phatak, and co-workers (DOI: 10.1002/adma.202513067).

Social games offer a rich and challenging environment to develop and evaluate complex robot behaviors. Social interactions with robots benefit from personalization, which requires person identification—a process that raises privacy concerns. Soft biometrics, however, offer a privacy-preserving alternative by enabling short-term identification without relying on private or sensitive features. In this work, we leverage a zero-shot Visual Question Answering (VQA) person identification system and adapt it to make Pepper play Guess Who? The identification module performance is firstly studied offline in the AveRobot dataset. Afterwards, it is integrated in a ROS based architecture that manages the game flow and enables natural verbal interaction. Experiments conducted with 29 subjects demonstrate that the system achieves identification performance nearly equivalent to that of hard biometric-based systems while also offering engaging and entertaining gameplay. Notably, user feedback reveals a high level of acceptance, highlighting that social gaming with robots is a promising avenue for developing and testing complex behaviors.

Abstract Fisher-matrix forecasts are presented for the cosmological surveys of the Javalambre Physics of the Accelerating Universe Astrophysical Survey (J-PAS) and the Subaru Prime Focus Spectrograph (PFS). The wide, low-redshift coverage of J-PAS and the high-density, high-redshift mapping of PFS are strongly complementary: combining the two reduces marginalized uncertainties on all primary parameters compared with either survey individually. Adding the joint J-PAS+PFS data to next-generation cosmic microwave background (CMB) measurements from the Simons Observatory and LiteBIRD yields an expected precision of σ (∑ m ν ) = 0.017 eV in the ΛCDM+∑ m ν + N eff framework, sufficient to disfavor the inverted neutrino hierarchy at 2.34 σ if the true mass sum equals the normal-ordering minimum. Motivated by recent DESI results, we also forecast within a w 0 w a CDM+∑ m ν + N eff cosmology, adopting the DESI DR2 best-fit values ( w 0 = −0.758, w a = −0.82) as fiducial. The combination CMB+J-PAS+PFS then delivers σ ( w 0 ) = 0.044 and σ ( w a ) = 0.18, corresponding to a 5.1 σ preference for a time-varying dark-energy equation of state. These findings show that J-PAS and PFS, especially when coupled with Stage IV CMB observations, will provide competitive tests of neutrino physics and the dynamics of cosmic acceleration.

Skin cancer (SC) is the most prevalent malignancy worldwide, with subtypes varying in aggressiveness: basal cell carcinoma tends to be locally invasive, squamous cell carcinoma has a higher metastatic risk, and melanoma remains the deadliest form. Current treatments such as surgery, radiotherapy, and systemic chemotherapy are associated with aesthetic and functional morbidity, recurrence, and/or systemic toxicity. Although targeted therapies and immunotherapies offer clinical benefits, their high cost and limited accessibility underscore the need for innovative, affordable alternatives. Metal-based compounds (metallopharmaceuticals) are promising anticancer agents due to their ability to induce oxidative stress, modulate redox pathways, and interact with DNA. However, clinical translation has been limited by poor aqueous solubility, rapid degradation, and low skin permeability. This review discusses the most recent preclinical findings on gold, silver, platinum, palladium, ruthenium, vanadium, and copper complexes, mainly in topical and systemic treatments of SC. Advances in chemical and physical enhancers, such as hydrogels and microneedles, and in drug delivery systems, including bacterial nanocellulose membranes and nanoparticles, as well as liposomes and micelles, for enhancing skin permeation and protecting the integrity of metal complexes are also discussed. Additionally, we examine the contribution of photodynamic therapy to SC treatment and the use of mathematical and computational modeling to simulate skin drug transport, predict biodistribution, and support rational nanocarrier design. Altogether, these strategies aim to bridge the gap between physicochemical innovation and clinical applicability, paving the way for more selective, stable, and cost-effective SC treatments.

Photocatalytic production of H2 or hydrocarbons requires multiple electrons, and therefore the absorption of multiple photons and accumulation of photoexcited charges. Alternatively, multiexciton generation (MEG) could loosen this requirement. Despite intense studies of the MEG process singlet fission (SF) for solar cells, its use in photocatalysis has only recently been demonstrated. Herein, we present a detailed investigation of electron transfer (ET) from the triplet pair state (TT) and triplet states in two SF-based tetracene dimers. We find that the TT state behaves similarly to the singlet and thus can be used to increase the lifetime of singlet reactivity. We also show that in these covalently linked SF dimers, where TT recombines to form one free triplet, achieving more than 100% ET is challenging. Together with these findings and the input from theoretical calculations, we discuss the possibilities and limitations of ET from these dimers. By highlighting strategies to mitigate detrimental TT recombination pathways, these insights provide design principles for next-generation SF chromophores tailored for solar energy conversion and photoredox catalysis.