arXiv subjects

Manuel Muñoz

Publications and source records attributed to Manuel Muñoz.

11 recordsLinked to original sources

arXiv2026

Nonlinear mode interactions under parametric excitation in a YIG microdisk

A pair of quantized spin-wave modes is driven by two-tone parallel pumping in a YIG microdisk. The nonlinear dynamics is experimentally investigated by probing the resulting steady state, which is found to critically depend on the chosen pair of modes, the detuning between the pump frequencies and the modes parametric resonance, as well as the temporal sequence of the two rf tones. A general theory of parametric excitation in confined structures based on magnetization normal modes is developed and quantitatively accounts for the observed dependence and non-commutative behaviors, which emerge from the interplay between the self and mutual nonlinear frequency shifts of the spin-wave modes. Owing to its high degree of external controllability and scalability to larger sets of modes, this dynamical system provides a model platform for exploring nonlinear phenomena and a promising route toward rf driven state mapping relevant to neuromorphic and unconventional computing.

cond-mat.mes-hall↗

arXiv2026

onepot CORE -- an enumerated chemical space to streamline drug discovery, enabled by automated small molecule synthesis and AI

The design-make-test-analyze cycle in early-stage drug discovery remains constrained primarily by the "make" step: small-molecule synthesis is slow, costly, and difficult to scale or automate across diverse chemotypes. Enumerated chemical spaces aim to reduce this bottleneck by predefining synthesizable regions of chemical space from available building blocks and reliable reactions, yet existing commercial spaces are still limited by long turnaround times, narrow reaction scope, and substantial manual decision-making in route selection and execution. Here we present the first version of onepot CORE, an enumerated chemical space containing 3.4B molecules and corresponding on-demand synthesis product enabled by an automated synthesis platform and an AI chemist, Phil, that designs, executes, and analyzes experiments. onepot CORE is constructed by (i) selecting a reaction set commonly used in medicinal chemistry, (ii) sourcing and curating building blocks from supplier catalogs, (iii) enumerating candidate products, and (iv) applying ML-based feasibility assessment to prioritize compounds for robust execution. In the current release, the space is supported by seven reactions. We describe an end-to-end workflow - from route selection and automated liquid handling through workup and purification. We further report validation across operational metrics (success rate, timelines, purity, and identity), including NMR confirmation for a representative set of synthesized compounds and assay suitability demonstrated using a series of DPP4 inhibitors. Collectively, onepot CORE illustrates a path toward faster, more reliable access to diverse small molecules, supporting accelerated discovery in pharmaceuticals and beyond.

physics.chem-ph↗

arXiv2025

Self-modulation instability in high power ferromagnetic resonance of BiYIG nanodisks

We study the high power ferromagnetic resonance (FMR) of perpendicularly magnetized BiYIG nanodisks where the uniaxial anisotropy almost compensates the shape anisotropy. We observe a strong saturation of the averaged magnetization upon moderately increasing the amplitude of the rf field and a broadening of the FMR line towards lower and higher magnetic field. Full micromagnetic simulations reveal that a self-modulation of the dynamic magnetization is responsible of this behavior. To get more insight into this unstable dynamics, it is analysed in terms of normal modes. The number of modes involved is found to rapidly increase above the critical threshold. Still, a normal modes model taking into account only a few of them and their mutual nonlinear couplings allows us to qualitatively reproduce the observed phenomenon. The normal modes analysis and micromagnetic simulations also predict a Suhl-like instability at larger excitation power when it is slowly increased from low values, and bistability. Using two-tone spectroscopy, we directly measure the self-modulation spectrum and provide experimental evidence of bistable dynamics. These findings open some perspectives of using high dimensional dynamics in magnetic nanostructures for unconventional information processing.

cond-mat.mes-hall↗

arXiv2023

Degenerate and non-degenerate parametric excitation in YIG nanostructures

We study experimentally the processes of parametric excitation in microscopic magnetically saturated disks of nanometer-thick Yttrium Iron Garnet. We show that, depending on the relative orientation between the parametric pumping field and the static magnetization, excitation of either degenerate or non-degenerate magnon pairs is possible. In the latter case, which is particularly important for applications associated with the realization of computation in the reciprocal space, a single-frequency pumping can generate pairs of magnons whose frequencies correspond to different eigenmodes of the disk. We show that, depending on the size of the disk and the modes involved, the frequency difference in a pair can vary in the range 0.1-0.8 GHz. We demonstrate that in this system, one can easily realize a practically important situation where several magnon pairs share the same mode. We also observe the simultaneous generation of up to six different modes using a fixed-frequency monochromatic pumping. Our experimental findings are supported by numerical calculations that allow us to unambiguously identify the excited modes. Our results open new possibilities for the implementation of reciprocal-space computing making use of low damping magnetic insulators.

cond-mat.mes-hall↗

arXiv2023

The BigScience ROOTS Corpus: A 1.6TB Composite Multilingual Dataset

As language models grow ever larger, the need for large-scale high-quality text datasets has never been more pressing, especially in multilingual settings. The BigScience workshop, a 1-year international and multidisciplinary initiative, was formed with the goal of researching and training large language models as a values-driven undertaking, putting issues of ethics, harm, and governance in the foreground. This paper documents the data creation and curation efforts undertaken by BigScience to assemble the Responsible Open-science Open-collaboration Text Sources (ROOTS) corpus, a 1.6TB dataset spanning 59 languages that was used to train the 176-billion-parameter BigScience Large Open-science Open-access Multilingual (BLOOM) language model. We further release a large initial subset of the corpus and analyses thereof, and hope to empower large-scale monolingual and multilingual modeling projects with both the data and the processing tools, as well as stimulate research around this large multilingual corpus.

cs.CL↗

arXiv2023

HERMES: qualification of High pErformance pRogrammable Microprocessor and dEvelopment of Software ecosystem

European efforts to boost competitiveness in the sector of space services promote the research and development of advanced software and hardware solutions. The EU-funded HERMES project contributes to the effort by qualifying radiation-hardened, high-performance programmable microprocessors, and by developing a software ecosystem that facilitates the deployment of complex applications on such platforms. The main objectives of the project include reaching a technology readiness level of 6 (i.e., validated and demonstrated in relevant environment) for the rad-hard NG-ULTRA FPGA with its ceramic hermetic package CGA 1752, developed within projects of the European Space Agency, French National Centre for Space Studies and the European Union. An equally important share of the project is dedicated to the development and validation of tools that support multicore software programming and FPGA acceleration, including Bambu for High-Level Synthesis and the XtratuM hypervisor with a level one boot loader for virtualization.

cs.OH↗

arXiv2020

Naturally occurring van der Waals materials

The exfoliation of two naturally occurring van der Waals minerals, graphite and molybdenite, arouse an unprecedented level of interest by the scientific community and shaped a whole new field of research: 2D materials research. Several years later, the family of van der Waals materials that can be exfoliated to isolate 2D materials keeps growing, but most of them are synthetic. Interestingly, in nature plenty of naturally occurring van der Waals minerals can be found with a wide range of chemical compositions and crystal structures whose properties are mostly unexplored so far. This Perspective aims to provide an overview of different families of van der Waals minerals to stimulate their exploration in the 2D limit.

cond-mat.mtrl-sci↗

arXiv2019

Nutation spectroscopy of a nanomagnet driven into deeply nonlinear ferromagnetic resonance

Strongly out-of-equilibrium regimes in magnetic nanostructures exhibit novel properties, linked to the nonlinear nature of magnetization dynamics, which are of great fundamental and practical interest. Here, we demonstrate that field-driven ferromagnetic resonance can occur with substantial spatial coherency at unprecedented large angle of magnetization precessions, which is normally prevented by the onset of spin-wave instabilities and magnetization turbulent dynamics. Our results show that this limitation can be overcome in nanomagnets, where the geometric confinement drastically reduces the density of spin-wave modes. The obtained deeply nonlinear ferromagnetic resonance regime is probed by a new spectroscopic technique based on the application of a second excitation field. This enables to resonantly drive slow coherent magnetization nutations around the large angle periodic trajectory. Our experimental findings are well accounted for by an analytical model derived for systems with uniaxial symmetry. They also provide new means for controlling highly nonlinear magnetization dynamics in nanostructures, which open interesting applicative opportunities in the context of magnetic nanotechnologies.

cond-mat.mes-hall↗

arXiv2018

Large spin-mixing conductance in highly Bi-doped Cu thin films

Spin Hall effect provides an efficient tool for the conversion of a charge current into a spin current, opening the possibility of producing pure spin currents in non-magnetic materials for the next generation of spintronics devices. In this sense, giant Spin Hall Effect has been recently reported in Cu doped with 0.5 % Bi grown by sputtering and larger values are expected for larger Bi doping, according to first principles calculations. In this work we demonstrate the possibility of doping Cu with up to 10 % of Bi atoms without evidences of Bi surface segregation or cluster formation, as studied by different microscopic and spectroscopic techniques. In addition, YIG/BiCu structures have been grown, showing a spin mixing conductance larger that the one shown by similar Pt/YIG structures. These results reflects the potentiality of these new materials in spintronics devices.

cond-mat.mtrl-sci↗

arXiv2017

Gate Tunable Photovoltaic Effect in MoS2 vertical P-N Homostructures

P-n junctions based on vertically stacked single or few layer transition metal dichalcogenides (TMDCs) have attracted substantial scientific interest. Due to the propensity of TMDCs to show exclusively one type of conductivity, n- or p-type, heterojunctions of different materials are typically fabricated to produce diode-like current rectification and photovoltaic response. Recently, artificial, stable and substitutional doping of MoS2 into n- and p-type has been demonstrated. MoS2 is an interesting material to use for optoelectronic applications due to the potential of low-cost production in large quantities, strong light-matter interactions and chemical stability. Here we report the characterization of the optoelectronic properties of vertical homojunctions made by stacking few-layer flakes of MoS2:Fe (n-type) and MoS2:Nb (p-type). The junctions exhibit a peak external quantum efficiency of 4.7 %, a maximum open circuit voltage of 0.51 V, they are stable in air and their rectification characteristics and photovoltaic response are in excellent agreement to the Shockley diode model. The gate-tunability of the maximum output power, the ideality factor and the shunt resistance indicate that the dark current is dominated by trap-assisted recombination and that the photocurrent collection depends strongly on the spatial extent of the space charge region. We demonstrate a response time faster than 80 ms and highlight the potential to integrate such devices into quasi-transparent and flexible optoelectronics.

cond-mat.mes-hall↗

arXiv2015

Generation of coherent spin-wave modes in Yttrium Iron Garnet microdiscs by spin-orbit torque

Spin-orbit effects [1-4] have the potential of radically changing the field of spintronics by allowing transfer of spin angular momentum to a whole new class of materials. In a seminal letter to Nature [5], Kajiwara et al. showed that by depositing Platinum (Pt, a normal metal) on top of a 1.3 $μ$m thick Yttrium Iron Garnet (YIG, a magnetic insulator), one could effectively transfer spin angular momentum through the interface between these two different materials. The outstanding feature was the detection of auto-oscillation of the YIG when enough dc current was passed in the Pt. This finding has created a great excitement in the community for two reasons: first, one could control electronically the damping of insulators, which can offer improved properties compared to metals, and here YIG has the lowest damping known in nature; second, the damping compensation could be achieved on very large objects, a particularly relevant point for the field of magnonics [6,7] whose aim is to use spin-waves as carriers of information. However, the degree of coherence of the observed auto-oscillations has not been addressed in ref. [5]. In this work, we emphasize the key role of quasi-degenerate spin-wave modes, which increase the threshold current. This requires to reduce both the thickness and lateral size in order to reach full damping compensation [8] , and we show clear evidence of coherent spin-orbit torque induced auto-oscillation in micron-sized YIG discs of thickness 20 nm.

cond-mat.mtrl-sci↗