Highlights
Unveiling the structure–magnetism interplay in the ferrimagnetic pyrochlore Gd2CrSbO7 with significant cryo–magnetocaloric performance
Communications Materials, 7, 6 (2026)
R. S. Silva Jr, J. E. Rodrigues, C. Santos, Ch Sahle, F. Serrano-Sánchez, H. L. Andersen, J. Gainza, A. Skorynina, N. Biskup, N. M. Nemes, E C. Passamani, J. L. Martínez, N. S. Ferreira & J. A. Alonso
In this work, with participation of Prof. Edson C. Passamani (UFES) and Prof. Nilson S. Ferreira (UFS), the ferrimagnetic pyrochlore Gd₂CrSbO₇ is investigated via diffraction, X-ray Raman spectroscopy, EXAFS, magnetization measurements, and first-principles calculations. The material exhibits 4f–3d exchange-driven ferrimagnetism, a Griffiths-like phase, and a Schottky anomaly. It achieves ΔSₘ ≈ 21 J/kg·K and refrigerant capacity ≈ 430 J/kg (0–7 T), comparable to benchmark cryogenic refrigerants but using earth-abundant elements. The main contributions are the introduction of a competitive, low-cost magnetocaloric material and advanced understanding of structure–frustration–magnetism interplay in mixed pyrochlore oxides.
Correspondence: nilson@academico.ufs.br
Quantum Geometry and the Electric Magnetochiral Anisotropy in Noncentrosymmetric Polar Media
Physical Review Letters, 135, 106602, (2025)
Pierpaolo Fontana, Victor Velasco, Chang Niu, Peide D. Ye, Pedro V. Lopes, Kaio E. M. de Souza, Marcus V. O. Moutinho, Caio Lewenkopf and Marcello B. Silva Neto
This work, with participation of Prof. Marcello B. S. Neto (UFRJ), connects electric magnetochiral anisotropy (eMChA) to the quantum metric of Bloch states. Using semiclassical transport theory including quantum metric dipole corrections, and second-harmonic transport measurements in 2D tellurium films, the authors demonstrate universal scaling γ(V) ∼ V⁻⁵ᐟ² under gate tuning. They also identify quantum geometry as the microscopic origin of eMChA, unifying nonreciprocal transport and band topology, with implications for topological electronics and CMOS-compatible rectification devices.
Correspondence: mbsn@if.ufrj.br
Unraveling the (1 × 1) and (1 × 2) reconstructed surface structures of SrTiO3 (1 1 0) single crystal
Applied Surface Science, 721, 1, 165401 (2026)
Alexandre Pancotti, Jenifer J. Silva, Mayron S. Castro, Abner de Siervo, Richard Landers, Pedro A.P. Nascente
This work, with participation of Prof. Abner de Siervo (UNICAMP), clarifies the atomic structure of (1×1) and (1×2) reconstructions on the polar SrTiO₃(110) surface. Combining XPS, LEED, XPD, and MSCD simulations optimized via genetic algorithms, the authors determine that the (1×2) reconstruction consists of a coexistence of ~60% TiO₄⁴⁺ and ~40% O₂⁴⁻ terminations on a (1×1) base. It is provided provide quantitative, element-selective structural determination of a complex polar oxide surface, crucial for interface engineering and controlled epitaxial growth in oxide heterostructures.
Correspondence: asiervo@ifi.unicamp.br
Metallicity-driven polar transitions in topological epilayers
Communications Physics, 8, 419 (2025)
Eduardo D. Stefanato, Nicolas M. Kawahala, Bianca A. Kawata, Paulo H. O. Rappl, Eduardo Abramof & Felix G. G. Hernandez
This study, with participation of Prof. Felix G. G. Hernandez (USP), explores Bi-doped Pb₀.₅Sn₀.₅Te topological epilayers using terahertz time-domain spectroscopy. The authors show that carrier concentration and type can be tuned non-monotonically via Bi doping, enabling control of the ferroelectric transition temperature (Tc = 65–95 K). Soft transverse optical phonon behavior reflects metallicity-dependent polar order. It demonstrate simultaneous control of ferroelectric and topological properties through carrier engineering, establishing a tunable platform for polar topological metals.
Correspondence: felixggh@if.usp.br
Disorder-induced damping of spin excitations in Cr-doped BaFe2As2
Physical Review Research, 8, L012028 (2026)
Marli R. Cantarino, Rafael M. P. Teixeira, K. R. Pakuszewski, Wagner R. da Silva Neto, Juliana G. de Abrantes, Mirian Garcia-Fernandez, P. G. Pagliuso, C. Adriano, Claude Monney, Thorsten Schmitt, Eric C. Andrade and Fernando A. Garcia
This study, with participation of Prof. Pascoal G. Pagliuso (UNICAMP), Eric C. Andrade (USP) and Fernando A. Garcia (USP), investigates how substitutional disorder affects magnetic excitations in the Hund’s metal Ba(Fe₁₋ₓCrₓ)₂As₂. Using high-resolution RIXS, ARPES, and theoretical modeling, the authors show that Cr doping introduces local magnetic moments that strongly interact with Fe-derived spin excitations. Magnons progressively soften and broaden with increasing Cr content, becoming overdamped at x = 0.085. A localized spin model incorporating disorder successfully reproduces the experimental trends. Complementary ARPES measurements reveal enhanced electronic localization and suppression of nematic band splitting. The work demonstrates that disorder, rather than carrier doping, may dominate magnetic excitation dynamics in Hund’s metals, providing key insight into the interplay between charge localization and spin fluctuations in iron-based systems.
Correspondence: fgarcia@if.usp.br