Magnetism, Volume 6, Issue 3 (September 2026) – 5 articles

The static and dynamic magnetic responses of symmetric Fe/Al/Fe trilayers were investigated as a function of the thickness of the nonmagnetic spacer layer thickness, with t_Al ranging from 0 to 2 nm. Samples showed ferromagnetic coupling between Fe layers for all values of t_Al, despite presenting characteristics of low-quality thin films, including high roughness and low-saturation magnetic moments. However, it was demonstrated that inclusion of a thin nonmagnetic Al spacer is an effective method to reduce the effective apparent damping parameter (α_app) of the dominant acoustic mode of the multilayered system. Specifically, α_app was reduced from 0.030 to 0.013 when the Al spacer thickness exceeded the characteristic roughness of the layers (t_Al ≥ 1.4 nm). This reduction coincided with the appearance of distinct acoustic and optical resonance modes, indicating a transition from a direct exchange-coupled regime dominated by pinholes to a regime dominated by dipolar coupling. This suggests that decoupling the ferromagnetic layers is a viable strategy for developing low-damping Fe-based materials, even in systems with significant structural imperfections. Full article

Nanocomposite rare-earth permanent magnets composed of exchange-coupled hard magnetic nanoparticles offer a promising route toward high-performance, rare-earth-efficient magnet technologies. In this work, we investigate the structural self-organization and magnetic hysteresis behavior of 40 nm Sm₂Co₁₇/Nd₂Fe₁₄B hybrid nanoparticles using a combined molecular dynamics (MD) and micromagnetic simulation framework. First, MD simulations are employed to study the Brownian motion and field-induced assembly of the hybrid nanoparticles at two particle concentrations (1 and 5 mg/cm³). In the absence of an external magnetic field, the nanoparticles display dispersed configurations governed by thermal fluctuations and interparticle interactions. Upon application of a high magnetic field (500 mT), the particles align into linear chain-like assemblies, with a more pronounced and rapid aggregation at higher concentration. Subsequently, micromagnetic calculations performed using the OOMMF are used to determine the magnetization reversal behavior of the assemblies. Quasi-static hysteresis loops at low field (40 mT) and room temperature reveal enhanced coercivity and remanence for field-aligned chain structures compared to randomly oriented particle ensembles. Additionally, increasing particle concentration amplifies the field-induced collective response due to stronger dipolar coupling. The combined MD–micromagnetic approach provides insight into structure–property relationships in magnetic nanocomposite systems and highlights the critical role of particle arrangement and concentration in determining magnet performance. These results contribute to the design principles for advanced nanostructured permanent magnets with tunable magnetic anisotropy and energy density. Full article

The emergence of all-d-metal Heusler alloys has opened up new pathways for the design of advanced functional materials. In this work, we employ first-principles electronic structure calculations to systematically investigate the electronic and magnetic properties of 27 all-d-metal Heusler compounds following the stoichiometry $X_{2}YZ$, where $X=$ Co, Rh, Ir, $Y=$ V, Cr, Mn, and $Z=$ Ti, Zr, Hf. Electronic band structure calculations show a consistent minority-spin pseudogap across the series, the width and characteristics of which are strongly dependent on the d-band broadening introduced by $4d$ (Rh, Zr) and $5d$ (Ir, Hf) transition metals. Magnetically, these materials largely follow the $M_{\mathrm{t}}=Z_{\mathrm{t}}-24$ Slater–Pauling rule, driven by exactly 12 occupied minority-spin bands at the $\Gamma$ point. Notably, substituting Co with Rh or Ir significantly redistributes the magnetization, drastically reducing the X-site spin magnetic moment while amplifying the spin magnetic moments on the Y-site atoms. This study provides a comprehensive understanding of the interplay between structural symmetry, orbital hybridization, and magnetism in all-d-metal Heuslers, highlighting their promise for future spintronic applications. Full article

We report on the finite temperature staggered spin susceptibility $\chi \left(Q\right)$ as a function of the mode–mode coupling constant $y_1$ in the self-consistent renormalization theory of two-dimensional antiferromagnetic spin fluctuations with zero-point quantum fluctuations just at the quantum critical point ($y_0$ = 0). We find that the value $y_1$ = 0.1 is a criterion to classify the effect of the zero-point spin fluctuations on the temperature dependence of $\chi \left(Q\right)$ into a Curie law for weak $y_1<$ 0.1 and a Curie–Weiss type or a power law type for strong $y_1>$ 0.1. The absence of a Curie–Weiss temperature can serve as an identifying criterion for QCP ($y_0$ = 0) in systems with weak mode–mode coupling ($y_1<$ 0.1). Experimental application on the $y_1$ classification is shown to several itinerant layered antiferromagnetic systems through an analysis of nuclear spin–lattice relaxation rates. Full article

This study investigates the use of magnetoelastic sensing for vibration-based structural health monitoring (SHM) of cementitious beam specimens under intact and damaged conditions. Prismatic mortar beams with dimensions of 160 × 40 × 40 mm³ were fabricated following standardized preparation procedures and equipped with annealed amorphous ferromagnetic ribbons, Metglas 2826MB3, for nondestructive magnetoelastic vibration sensing. The specimens were tested under free-vibration conditions in a simply supported configuration, and their vibration response was measured using a detection coil and subsequently analyzed using MATLAB software. The undamaged specimen exhibited a dominant resonance frequency at 6531 Hz, which closely corresponded to the fourth bending mode predicted by Euler–Bernoulli beam theory. Controlled notch-shaped cracks with varying locations and depths were subsequently introduced to evaluate the sensitivity of the sensing system to structural damage. Experimental results showed that the frequency shift is strongly influenced by the location of damage relative to the modal nodes, with maximum sensitivity observed between nodal regions and minimal variation near the nodes. Furthermore, increasing notch-shaped crack depth produced progressively larger frequency shifts, revealing a monotonic and non-linear relationship between damage severity and dynamic response. Polynomial fitting and 3D surface analysis further highlighted the combined influence of crack location and depth on the measured frequency variation. The findings confirm that the magnetoelastic sensor is capable of accurately detecting and magnetically transmitting the vibration state and damage-induced changes in cementitious structures, demonstrating high sensitivity and strong potential for application in vibration-based structural health monitoring systems, particularly in materials characterized by strong vibration damping. Full article