arXiv subjects

Gianguido Baldinozzi

Publications and source records attributed to Gianguido Baldinozzi.

4 recordsLinked to original sources

arXiv2025

Kitaev interactions of the spin-orbit coupled magnet UO2

Uranium dioxide, UO$_2$, is a canonical example of a magnetic material with strong spin-orbit coupling. Here, we present a study of the magnetic diffuse scattering measured on a polycrystalline sample of UO$_2$, which we interpret in terms of its magnetic interactions between U$^{4+}$ magnetic moments. By refining values of the magnetic interaction parameters to magnetic diffuse-scattering data measured above the magnetic ordering transition temperature, we show that the dominant magnetic coupling in UO$_2$ is a bond-dependent interaction analogous to the Kitaev model of honeycomb magnets. We compare our experimental results with published theoretical predictions and experimental measurements of the magnetic excitation spectrum. Our results suggest that magnetic materials with $f$-electron magnetic ions, particularly actinides, may be promising candidates for realising Kitaev magnetism, and highlight the role that magnetic diffuse-scattering data can play in identifying such materials.

cond-mat.str-el↗

arXiv2024

A Simple Modeling for Gas Release During Annealing of Irradiated Nuclear Fuel

We have developed a gas flow model in the spent nuclear fuel during the annealing. It postulates that the gas release during an isothermal plateau at 1200{\textdegree}C corresponds to the equilibrium between overpressure gas reservoirs in the fuel sample connected to the free surface at atmospheric pressure.

cond-mat.mtrl-sci↗

arXiv2023

Charge localization, frustration relief, and spin-orbit coupling in U$_3$O$_8$

Research efforts on the low temperature magnetic order and electronic properties of U$_3$O$_8$ have been inconclusive so far. Reinterpreting neutron scattering results, we use group representation theory to show that the ground state presents collinear out-of-plane magnetic moments, with antiferromagnetic coupling both in-layer and between layers. Charge localization relieves the initial geometric frustration, generating a slightly distorted honeycomb sublattice with Néel order. We show, furthermore, that spin-orbit coupling has a giant effect on the conduction band states and band gap value. Our results allow a reinterpretation of recent optical absorption measurements.

cond-mat.str-el↗

arXiv2022

Correlation of strontium anharmonicity with charge-lattice dynamics of the apical oxygens and their coupling to cuprate superconductivity

Cu K edge X-ray absorption spectra of overdoped superconducting $YSr_2Cu_{2.75}Mo_{0.25}O_{7.54}$ and $Sr_2CuO_{3.3}$ show a remarkably strong correlation of their superconductivity with the local dynamics of their Cu-Sr and Cu-apical-O pairs. This finding that the entire alkaline earth cation-apical O "dielectric" layer has an active role in the unusual electronic properties of cuprates has not been previously considered and has far reaching implications. We develop this idea of a possible role for the apical oxygen charge dynamics via a soft mode of the Sr by applying Kuramoto's synchronization technique to exact diagonalization calculations of two neighboring Cu-apical O pairs bridged by Sr and a planar O atom. These calculations show a first order phase transition to a synchronized state of the Internal Quantum Tunneling Polarons (IQTPs) in which a fraction of the hole originally confined to the apical O atoms of the cluster is transferred onto the planar O. This combination of experimental results and theory demonstrates that the Sr-O dielectric layer of cuprates most likely plays an important role in high temperature superconductivity via its collective charge dynamics that extends into the $CuO_2$ conducting planes.

cond-mat.supr-con↗