arXiv subjects

Iván Rivilla

Publications and source records attributed to Iván Rivilla.

3 recordsLinked to original sources

arXiv2026

Galvanic intercalation of molecular cations into van der Waals materials

The intercalation of molecular species between the layers of van der Waals (vdW) crystals is a powerful approach to combine the remarkable physical properties of vdW materials with the chemical versatility of organic molecules. However, the full transformative potential of molecular intercalation remains underexplored, largely due to the lack of simple, broadly applicable methods that preserve high crystalline quality down to the few-layer limit. Here, we introduce a simple galvanic approach to intercalate different molecules into various vdW materials under ambient conditions, leveraging the low reduction potential of selected metals. We employ our method, which is particularly well-suited for the in-situ intercalation of few-layer-thick crystals, to intercalate nine vdW materials, including magnets and superconductors, with molecules ranging from conventional alkylammonium ions to metallorganic and bio-inspired chiral cations. Notably, intercalation leads to an unprecedented transition from antiferromagnetic to ferrimagnetic ordering in α-RuCl3 and to a molecule-dependent enhancement of the superconducting transition in 2H-TaS2. These results establish our approach as a versatile technique for engineering atomically thin quantum materials and heterostructures, unlocking the transformative effects of molecular intercalation.

cond-mat.mtrl-sci↗

arXiv2025

Degenerate monolayer Ising superconductors via chiral-achiral molecule intercalation

Engineering unconventional superconductors is a central challenge in condensed matter physics. Molecule-intercalated TaS2 superlattices have recently been reported to host such states, yet their origin remains debated, underscoring the urgent need for controlled, device-integrated studies. Here, we report that nanometer-thick TaS2 and NbSe2 intercalated with chiral and achiral organic cations instead exhibit robust monolayer-like Ising superconductivity, with no evidence of unconventional pairing. Using high-quality superlattices integrated into devices, we disentangle the roles of interlayer coupling and charge transfer in shaping their superconducting behavior. In TaS2, intercalation induces interlayer decoupling regardless of molecular size or symmetry, yielding monolayer-like Ising superconductivity. NbSe2 instead retains quasi-three-dimensional transport, with a gradual Ising enhancement and near-monolayer behavior only at the largest interlayer spacing. Transport remains reciprocal across all superlattices, consistent with preserved inversion symmetry and incompatible with parity-breaking superconductivity and noncentrosymmetric monolayers. We attribute the behavior to electronically detached monolayers with opposite spin-split bands, coupled through thermal and tunneling processes, which overall preserve inversion symmetry. These findings establish molecular intercalation compounds as a robust, device-ready, platform for engineering advanced superconducting superlattices.

cond-mat.supr-con↗

arXiv2019

Towards a background-free neutrinoless double beta decay experiment based on a fluorescent bicolor sensor

Searching for neutrinoless double beta decays ($β\beta0ν$) is the only practical way to establish if the neutrinos are their own antiparticles. Due to the smallness of neutrino masses, the lifetime of $β\beta0ν$ is expected to be at least ten orders of magnitude smaller than the noise associated with the natural radioactive chains. A positive identification of $β\beta0ν$ decays requires, ultimately, finding a signal that cannot be mimicked by radioactive backgrounds. This signal could be the observation of the daughter atom in the decay, since no known background processes induce a Z+2 transformation. In particular, the $β\beta0ν$ decay of Xe-136 could be established by detecting the doubly ionised daughter atom, Ba$^{2+}$. Such a detection could be achieved via a sensor made of a monolayer of molecular indicators. The Ba$^{2+}$ would be captured by one of the molecules in the sensor, and the presence of the single chelated indicator would be subsequently revealed by a strong fluorescent response from repeated interrogation with a laser system. Here we describe a fluorescent bicolor indicator that binds strongly to Ba$^{2+}$ and shines very brightly, shifting its emission colour from green to blue when chelated in dry medium, thus allowing the unambiguous identification of single barium atoms in the sensor, and permitting a positive identification of the $β\beta0ν$ decay of Xe-136 in a gas chamber, that could led to a background-free experiment.

physics.ins-det↗