arXiv subjects

Antonio Corona

Publications and source records attributed to Antonio Corona.

2 recordsLinked to original sources

arXiv2026

A comparison of the spin-phonon behaviour of Fe$_2$P-based magnetocaloric materials

Magnetic refrigeration can provide an environmentally friendly technology to reduce significantly the energy consumption of cooling devices. To retain the sustainability of the device, all parts must be made from abundant materials, excluding e.g. rare earth elements. As such, materials based on Fe$_2$P have shown great potential for magnetocaloric devices. In this study, Fe$_2$P and FeMnP$_{0.55}$Si$_{0.45}$, have been studied using magnetometry, neutron scattering and theoretical modelling with the aim to understand the ferromagnetic transition, related to the magnetocaloric effect. Analysis of the diffraction data of Fe$_2$P showed that it is the Fe$_{3g}$-site that drives the magnetic transition as the Fe$_{3f}$ does not have any magnetic contribution at the magnetic transition temperature. For FeMnP$_{0.55}$Si$_{0.45}$, the magnetic transition is more gradual, on both sites, with coexistence of the para- and ferromagnetic phases close to the magnetic transition. The temperature dependent magnetic structure behaviour are well in agreement with our first principles calculations. Both Fe$_2$P and FeMnP$_{0.55}$Si$_{0.45}$ showed two distinct regions, at different length scales, in their S(\textbf{Q},$ω$) spectra. The two length scales can be modelled using a different set of magnetic spin states (S), using S$\rm _{Fe}$~=~2 and S$\rm _{Mn}$~=~2.5, consistent with the ground state of the magnetic atoms. QENS at low Q (Q~\textless{}~0.5~Å) shows similar magnetic processes in both compounds with uncorrelated magnetism below the magnetic transition temperature. The uncorrelated state highlights that the magnetic anisotropy does not play a major role in the formation of the magnetic state. Furthermore, this emphasises the existence of a two part system in FeMn(P,Si)-based compounds, that drives the magnetic transition and in turn the magnetocaloric effect.

cond-mat.mtrl-sci↗

arXiv2025

UNAGI: A Conceptual Electrodynamic Tethered Spacecraft Demonstration Mission for Propellantless Landing on Io

This paper presents UNAGI, a novel spacecraft mission developed by Spartan Space Systems, a student engineering team at San Jose State University, aiming for the first controlled landing on Jupiter's volcanically active moon Io. Inspired by the Japanese freshwater eel's agility, UNAGI employs an electrodynamic tether system that interacts with Jupiter's magnetic field to generate Lorentz forces, enabling dynamic modulation of the spacecraft's velocity without the need for traditional propellant. This system allows the spacecraft to precisely match Io's orbital velocity, similar to a surfer riding a wave. By optimizing tether current and orientation, UNAGI transitions from an outer Jovian insertion orbit to an orbit around Io, achieving a controlled landing for on-surface science operations. The landing is strategically timed, leveraging the gravitational influence of Jupiter and its moons to decelerate descent and mitigate impact forces. UNAGI leverages technologies from missions like Juno, JUICE, and Europa Clipper to ensure reliable operation in the challenging Jovian environment. The mission follows a phased approach, including cruise, orbital insertion, tether deployment, Jovian orbital operations, and final descent, with extensive risk mitigation through simulations and experimental validation. The concept supports rideshare integration on future NASA or ESA missions or a dedicated launch, emphasizing cost effectiveness and adaptability. UNAGI carries a scientific payload including infrared spectrometers, magnetometers, seismometers, and chromatographs, designed to probe Io's interior dynamics, volcanic activity, tectonic deformation, and magnetospheric interactions. This mission aims to advance understanding of Io's geophysical processes and Jupiter system dynamics, setting a new standard for deep space exploration of extreme environments.

astro-ph.IM↗