Iron-cementite (Fe-Fe3C) "core-shell" magnetic nanoparticles embedded in a carbon matrix were synthesized via solid-state pyrolysis of ferrocene. The average nanoparticle diameter is approximately 20 nm, with a composition ratio of Fe to Fe3C of about 2:1, which correlates well with the saturation magnetization (Ms) measured at room temperature. The efficacy of magnetic hyperthermia as a function of nanoparticle concentration, as well as the frequency and amplitude of the alternating magnetic field, was systematically investigated. The Rosensweig theory was applied to calculate the relaxation time (tau) as 2.9 x 10-7 seconds by fitting the frequency-dependent specific loss power (SLP) values at a constant frequency. Using this approach, the equilibrium magnetic susceptibility (chi 0) was also estimated at 0.22 +/- 0.03 through approximations of frequency-dependent SLP values at a fixed magnetic field amplitude. Additionally, chi 0 was determined at 0.33 +/- 0.04 by fitting the field-dependent SLP data at a constant frequency, incorporating a conservative estimate of field-dependent susceptibility based on the Langevin model. Both methods yielded chi 0 values that overlap with the experimental value of 0.27 +/- 0.03 within their respective error margins. These results suggest that the primary assumptions of the employed theoretical model are consistent with the experimental conditions. A numerical model simulating a single nanoparticle embedded in a fluid was developed using COMSOL Multiphysics to compare with the experimental concentration-dependent SLP data. The obtained results enable determination of the critical concentration in suspensions, beyond which the assumption of non-interacting particles no longer holds.

High-entropy alloy nanoparticles (HEA NPs) constitute an interesting material class with high potential as heterogeneous catalysts due to their exceptional compositional and structural tunability and the complex interplay of different element-specific surface sites. Laser ablation in liquids (LAL) is a kinetically controlled synthesis method that allows the generation of colloidal HEA NPs. With CrMnFeCoNi-NPs, a facile control of the NP phase structure, switching between crystalline and amorphous via applied laser pulse duration, has been previously reported, attributed to the different particle solidification times and metalloidic carbon incorporation pathways. However, neither the replacement of the oxygen-affine Mn by the sp2-carbon coupling element Cu, nor the transferability of the pulsed laser fabrication process from bulk target to micropowder feedstock processing, has been studied. In the present work, we use scanning transmission electron microscopy, equipped with energy-dispersive X-ray spectroscopy (STEM-EDX), high-resolution transmission electron microscopy (HRTEM), selected area electron diffraction (SAED), and X-ray diffraction (XRD) to demonstrate the transferability of internal phase structure tunability to the CrFeCoNiCu alloy and confirm ns- and ps-pulsed LAL yielding amorphous and crystalline HEA NPs, respectively, with diameters of 10-40 nm. Furthermore, we examine the generation of CrMnFeCoNi and CrFeCoNiCu nanoparticles by scalable, fully continuous ns-pulsed microparticle laser fragmentation in liquid (MP-LFL) using a high-power UV-laser and find the emergence of amorphous phase structures only in the Cu-containing nanoparticles, a phenomenon we attribute to copper-catalyzed carbon incorporation into the HEA NPs. These studies are complemented by a detailed characterization of the surface electrochemistry of the HEA NPs via alkaline cyclic voltammetry (CV) and elemental compositions in surface-near volumes, quantified by X-ray photoelectron spectroscopy (XPS). We elucidate that primarily the chemical composition (Mn vs. Cu) and, only to a lower extent, the phase structure (amorphous vs. crystalline) determine the surface potential, electrochemical stability upon multiple CV cycling, and surface element distribution of the particles. Finally, the activity of the HEA NPs in the oxygen evolution reaction (OER) is evaluated via linear sweep voltammetry (LSV), where we find amorphous CrMnFeCoNi HEA NPs to be more active (lower overpotential, higher current density) than their crystalline counterparts, motivating future application-focused work and transfer to other material systems and relevant reactions.

This paper discusses the effect of Ge composition (x) on the static and dynamic magnetic properties of epitaxial Fe100-xGex films with vaious Ge compsitions (x) between 7.2-19.2. The saturation magnetostriction varied from negative value to positive one at approximately x = 13.5 as x increased. The in-plane and out-of-plane effective damping constants followed a similar trend with regard to x and their values were reduced regardless of x, suggesting that the extrinsic damping contribution from structural and/or magnetic inhomogeneity is negligible. Furthermore, there is the correlation between the in-plane effective damping constant and the saturation magnetostriction in the range of x between 10.9-17.6 which not only the A2 phase but also B2 phase exists. These results suggest that the structural change in the epitaxial Fe-Ge thin films is one of the dominant factors for the correlation between the in-plane effective damping constant and saturation magnetostriction.

Powder bed fusion (PBF) is a promising but challenging method for the additive manufacturing (AM) of magnetic Nd-Fe-B alloys due to the material’s inherent brittleness, oxidation sensitivity, and complex phase evolution. In this study, crack-free and dense near-net-shape parts were successfully produced via electron beam powder bed fusion (PBF-EB) using a stress-reducing spot melting strategy. Identical gas-atomized powder (68.7Fe-19.2Nd-1.7B-1.9Ti-2.5Co-4.3Zr-1.4Pr) was also processed by laser powder bed fusion (PBF-LB). While PBF-EB samples showed high density and mechanical integrity, the PBF-LB parts suffered from significant porosity and cracking despite preheating, indicating insufficient thermal stress management. Magnetic characterization revealed coercivities up to 9.3 kA/m (11.7 mT) and specific saturation magnetization values of 136 Am2/kg at 310 K for PBF-EB samples. In contrast, PBF-LB samples exhibited considerably higher but still low coercivity (127 kA/m; 0.16 T) compared to the powder state, attributed to oxidation, phase inhomogeneity, and structural discontinuities. PBF-EB samples remained largely unaffected by post-processing heat treatment up to 1050 °C, suggesting a stable near-equilibrium microstructure already formed during PBF processing. PBF-LB samples underwent a breakdown of the initial finely structured matrix, the emergence of soft magnetic α-Fe phases and consequently magnetic deterioration, highlighting the metastable nature of their as-built state. These findings emphasize that magnetic performance in AM of rare-earth (RE) lean Nd-Fe-B alloys is governed not only by thermal exposure but also by process-inherent solidification kinetics and oxidation sensitivity. By highlighting the critical importance of decoupling thermal effects and solidification dynamics in AM, a framework for future alloy and process design strategies aimed at achieving high-performance, binder-free permanent magnets is provided.

High-entropy alloys (HEAs) containing 3d transition metals provide a versatile platform for tuning magnetic properties due to their chemically complex local environments and competing exchange interactions. In this work, CoMnFeNi HEA ribbons were synthesized by melt spinning (MS) directly from elemental powders, combining alloy formation and rapid solidification in a single step. The effect of wheel speed (10–40 m/s) on the structure, chemical homogeneity and magnetic behavior was systematically investigated. All ribbons crystallize in a single-phase FCC structure, while variations in the relative intensities of the (111) and (200) reflections indicate the development of the solidification-induced crystallographic texture. The MS10 ribbon remains chemically homogeneous, whereas MS40 exhibits nanoscale Mn-Fe segregation. These processing-induced differences lead to magnetic behavior ranging from weak paramagnetism in the MS10 to pronounced ferromagnetism in the MS20, MS30, and MS40 ribbons. Exchange-bias effects observed at 5 K further indicate ferromagnetic-antiferromagnetic exchange coupling associated with nanoscale chemical heterogeneity. Overall, the results demonstrate that wheel speed during melt spinning provides an effective route to tune the magnetic properties of CoMnFeNi ribbons through its influence on crystallographic texture, microstructure, and chemical homogeneity.

Permanent magnets containing rare earth elements are essential components for the electrification of society. Ce(Co1-xCux)(5) permanent magnets are a model system known for their substantial coercivity, yet the underlying mechanism remains unclear. Here, we investigate Ce(Co0.8Cu0.2)(5.4) magnets with a coercivity of similar to 1 T. Using transmission electron microscopy (TEM) and atom probe tomography (APT), we identify a nanoscale cellular structure formed by spinodal decomposition. Cu-poor cylindrical cells (similar to 5-10 nm in diameter, similar to 20 nm long) have a disordered CeCo5-type structure and a composition Ce(Co0.9Cu0.1)(5.3). Cu-rich cell boundaries are similar to 5 nm thick and exhibit a modified CeCo5 structure, with Cu ordered on the Co sites and a composition Ce(Co0.7Cu0.3)(5.0). Micromagnetic simulations demonstrate that the intrinsic Cu concentration gradients up to 12 at.% Cu/nm lead to a spatial variation in magnetocrystalline anisotropy and domain wall energy, resulting in effective pinning and high coercivity. Compared to Sm2Co17-type magnets, Ce(Co0.8Cu0.2)(5.4) displays a finer-scale variation of conventional pinning with lower structural and chemical contrast in its underlying nanostructure. The identification of nanoscale chemical segregation in nearly single-phase Ce(Co0.8Cu0.2)(5.4) magnets provides a microstructural basis for the long-standing phenomenon of "giant intrinsic magnetic hardness" in systems such as SmCo5-xMx, highlighting avenues for designing rare-earth-lean permanent magnets via controlled nanoscale segregation.

Nanocrystalline $\text{CoCrFeMnNi} \text{Ag}_{\mathrm{x}}(\mathrm{x}=0; 1; 2.5; 5.5$ at. %) high entropy alloy (HEA) powders, produced via rapid two-step highenergy ball milling (HEBM) in Ar, were consolidated into bulk samples by spark plasma sintering (SPS) at 700 K and 1000 K. SPSconsolidated HEAs exhibit complex magnetic behavior, with the critical temperature decreasing from $\mathbf{1 0 1 K}$ ($\mathbf{A g}$-free $\mathbf{C o C r F e M n N i}$) to 78 K (5.5 at. %). Ag-free CoCrFeMnNi sintered at 1000 K formed a single-phase fcc alloy with uniform elemental distribution and Vickers microhardness ($\mathbf{H V}_{0.2}$) of 2.4 GPa. Ag addition created distinct powder microstructures, from Ag-segregated regions (1 and 2.5 at. %) to uniform Ag distribution ($5.5 \text{at}. \%$), increasing $\text{HV}_{0.2}$ by 12% (to 2.7 GPa) in SPS-consolidated HEAs. In-field annealing (up to $700 \mathrm{K}, 9 \mathrm{T})$ enhanced magnetization $(M)$, coercivity $\left(H_{c}\right)$, and remanence $\left(M_{r}\right)$. $\text{CoCrFeMnNi}-\mathbf{A g}_{x}(\mathbf{x}=\mathbf{5. 5}$ at. %, $\mathbf{7 0 0 K})$ showed a tenfold rise in $M(9 \mathrm{T}, 310 \mathrm{K})$ to $38.7 \text{Am}^{2} / \text{kg}, H_{\mathrm{c}}=46 \text{kA} / \mathrm{m}$, and $M_{\mathrm{r}}=12.1 \text{Am}^{2} / \text{kg}$.

Birds use a variety of navigational strategies, including the geomagnetic field, especially when other cues are not available, such as under overcast or nocturnal conditions. Magnetite particles in the beak, cryptochromes in the eye, cellular ion-channel alterations, and changes in the vestibular system have been proposed to explain magnetoreception, but the exact mechanisms remain debated. Here, we used physical, morphological, functional, and genomic assays to identify the presence of superparamagnetic macrophages in the liver. We found that after macrophage depletion, pigeons flying under overcast conditions lacked their usual orientation capabilities. Orientation was unimpaired in birds without macrophages when the sun was visible, suggesting that this was their primary cue. We propose that in homing pigeons, superparamagnetic macrophages in the liver are required for finding magnetic direction.

Electrosynthesis of H2O2 is attractive for its environmental sustainability and cost-effectiveness, yet is impeded by the sluggish reaction kinetics and low selectivity triggered by the competing 4e- pathway. Here, a model transition-metal-based multimetallic aerogel was designed using CrMnFeCoNi HEA nanoparticles from nanosecond-pulsed laser synthesis in liquids, along with three exemplary quaternary systems without Co, Fe, and Ni, respectively. Among them, the resulting CrMnFeCoNi HEA aerogel exhibits the highest H2O2 selectivity of 95% and the lowest transferred electron number of 2.1, as well as good stability of nearly 100% H2O2 selectivity after 10k cycles. Furthermore, the as-prepared CrMnFeCoNi aerogel reaches a maximum H2O2 yield of 2.34 mmol h-1 c m d i s k - 2 and demonstrates an efficient decolorization ability for organic pollutants (e.g., Methylene blue or Rhodamine B). This outstanding performance is attributed to the synergetic effects of the various metals and the configurational entropy contribution, enabling a favored distribution of surface atom arrangements and optimal binding energies during electrochemical reactions. This work not only provides a novel perspective for manipulating HEA aerogels but also presents a promising alternative for industrial H2O2 production and water treatment.

Magnetic nanoparticles have proven invaluable for biomechanical investigations due to their ability to exert localized forces. However, cellular delivery of exogenous magnetic agents often results in endosomal entrapment, thereby limiting their utility for manipulating subcellular structures. This study characterizes and exploits fully genetically controlled biomineralization of iron-oxide cores inside encapsulin nanocompartments to enable magnetic-activated cell sorting (MACS) and magnetic cell manipulation. The fraction of MACS-retained cells showed substantial overexpression of encapsulins and exhibited both para- and ferrimagnetic responses with magnetic moments of 10-15 A m2 per cell, comparable to standard exogenous labels for MACS. Electron microscopy revealed that MACS-retained cells contained densely packed agglomerates of approximate to 30 nm iron oxide cores consisting of ultrafine quasicrystalline ordered nuclei within an amorphous matrix of iron, oxygen, and phosphorus. Scanning transmission X-ray microscopy, X-ray absorption spectroscopy, and Raman microspectroscopy confirmed that the iron-oxide species are consistent with ferric oxide (Fe2O3). In addition, the encapsulin-overexpressing MACS-retained cells can be manipulated by a magnetic needle and regrown in patterns determined by magnetic gradients. This study demonstrates that the formation of quasicrystalline iron oxide with mixed para/ferrimagnetic behavior in the cytosol of mammalian cells enables magnetic manipulation without the delivery of exogenous agents.

We determined the temperature dependence of the first-order magnetocrystalline anisotropy constants of the orthorhombic ferromagnetic MAB-phase Fe2AlB2. For this we prepared Fe2AlB2 single crystals by high-temperature solution growth and investigated them with the two independent measurement techniques of magnetometry and broadband ferromagnetic resonance. We find that Fe2AlB2 is almost an easy-plane magnet with the out-of-plane anisotropy constant [Kc & lowast;(10 K) = (1.03 +/- 0.02) MJm-3] and the in-plane anisotropy constant [Kb & lowast;(10 K) = (0.11 +/- 0.03) MJ m-3] deviating by a factor of 10. Finally, we determined alpha from the Callen and Callen power law K(T)/K (0) =(M(T)/M(0))alpha for Kc & lowast;as alpha Kc & lowast;=3, which corresponds to a single-ion uniaxial anisotropy.

High entropy oxides (HEOs) have recently attracted increasing attention due to their remarkable properties and relatively low cost. Herein we report a simple, highly scalable, and low temperature method for synthesizing spinel (FeNiCoCuZn)3O4 (HEO). We heated an aqueous solution containing divalent cations in high alkali environments to temperatures of 25 - 95 °C for 24 h under atmospheric pressure. The HEO, synthesized at 95 °C for 24 h in 1 M KOH, was paramagnetic at room temperature, with a magnetic mass susceptibility of χ = (7.5 ± 0.2) × 10-7 m3·kg-1. It demonstrated stable electrochemical lithium storage performance, with a gravimetric capacity of ∼300 mAh·g-1 at 100 mA·g- 1. It was also active in the electrocatalytic oxygen evolution reaction with an overpotential of 460 mV in alkaline media. The band gap energies were in the range of 2.4 eV. Our advancement in the synthesis and processing of transition metal-based HEOs will undoubtedly render them a viable solution for next generation materials for energy production and storage.

Inertial spin dynamics alters the resonant spin wave excitation resulting in the modification of the resonance field and relaxation in microwave spectroscopy of ferromagnets described by the conventional Landau-LifshitzGilbert (LLG) equation. Here we present a complete theoretical framework which quantitatively predicts the dynamic response of the magnetization for ferromagnetic systems exhibiting inertia. We compute the tensor of the high-frequency magnetic susceptibility analytically using the linearization of the inertial LLG equation, with fewer approximations than in the inertial Smit-Beljers approach. Our solution yields the precession (ferromagnetic resonance) and nutation resonance frequency, relaxation and intensity for an arbitrary free energy density, allowing straightforward quantitative analysis of inertial effects in magnetic resonances. Using the typical parameters of permalloy as an example we calculate the impact of materials parameters including Gilbert damping and inertial relaxation time on the conventional magnetic resonant response as well as the amplitude, linewidth, and frequency of the typically subterahertz nutation resonance.

Recent studies on thermal annealing of Ni-Mn-based alloys at moderate temperatures (<= 750 K) have led to the discovery of novel functionalities. Understanding the microstructural changes that occur during this process is crucial for optimizing annealing conditions to enhance material properties. Herein, we conduct transmission electron microscopy (TEM) experiments to examine the microstructural evolution and the formation of intermediate states in post-annealed Ni50Mn45In5 alloys subjected to thermal treatment at temperatures ranging from 650 K to 750 K. The diffuse scattering and satellite reflections observed in the diffraction patterns of as-cast Ni50Mn45In5 alloys upon thermal annealing are attributed to local enrichment of In elements, leading to the decomposition of the alloy into an L10-NiMn matrix and L21-Ni2MnIn nanoprecipitates. We further conduct in situ heating TEM observations on thin specimens. While both ex situ and in situ TEM experiments reveal similar trends in the processes of alloy decomposition and nanoprecipitation, the influence of sample thickness and vacuum conditions during in situ heating TEM must be carefully considered. Additionally, we analyze the magnetization curves and magnetic domains of the post-annealed samples to establish a relationship between the microstructural features and the magnetic properties of the dual-phase system, consisting of antiferromagnetic L10-NiMn matrix and ferromagnetic L21-Ni2MnIn nanoprecipitates. Our findings on Ni50Mn45In5 alloys provide insights that can be applied to other Ni-Mn-based alloys and potentially to a broader range of materials, offering a framework for understanding alloy decomposition, nanoprecipitation, and their impact on magnetic properties.

Developing effective non-noble metal electrocatalysts for the oxygen evolution reaction (OER) remains challenging due to limited active sites, poor electronic conductivity, and high overpotentials associated with the conventional adsorbate evolution mechanism (AEM). To address these limitations, a one-step spray drying method is employed to assemble high-surface-area La0.8Sr0.2CoO3 nanoparticles (LSCO-NP) into hierarchical supraparticles with ≈65% porosity and interconnected meso-/macropore networks. This architecture not only accelerates ion diffusion and interparticle electron transfer but also induces a mechanistic switch from the AEM to the lattice oxygen oxidation mechanism (LOM). La0.8Sr0.2CoO3 supraparticles (LSCO-SP) demonstrate significantly enhanced OER performance, requiring ∼300 mV lower overpotential at 100 mA cm-2 after 1 h compared to LSCO-NP. Moreover, LSCO-SP exhibit faster catalytic kinetics, evidenced by a smaller Tafel slope of 76.2 mV dec-1 versus 82.5 mV dec-1 and lower charge transfer resistance of 1.11 Ω versus 1.31 Ω for LSCO-NP. Structural analyses confirmed that the LSCO-SP maintained their integrity under OER conditions. Furthermore, post-mortem X-ray photoelectron spectroscopy (XPS) and electron paramagnetic resonance (EPR) analyses reveal an increased formation of oxygen vacancies (Ovac) in LSCO-SP, confirming that the supraparticle design tunes the lattice oxygen-mediated mechanism-oxygen vacancy site mechanism (LOM-OVSM), enhancing OER performance. The hierarchical structure of LSCO-SP highlights their potential as a novel building block for catalyst layers in renewable energy applications.

The human iron storage protein ferritin represents an appealing template to realise a semisynthetic magnetic nanoparticle (MNP) for spatial manipulation or inductive heating applications on a nanoscale. Ferritin consists of a protein cage of well-defined size (12 nm), which is genetically modifiable, biocompatible, and into which a magnetic core is synthesised. Here, we probe the magnetic response and hence the MNP’s suitability for (bio-)nanotechnological or nanomedical applications, when the core is doped with 7 % cobalt or 7 % zinc, in comparison to the undoped iron oxide MNP. The samples exhibit almost identical core and hydrodynamic sizes, along with their tunable magnetic core characteristics as verified by structural and magnetic characterisation. Cobalt doping significantly increased the MNP’s anisotropy and hence the heating power in comparison to the other magnetic cores with potential application as a mild heat mediator. Spatial magnetic manipulation was tested with MNPs inside droplets, the cell cytoplasm, or the cell nucleus, where the MNP surface conjugation with mEGFP and poly(ethylene glycol) gave rise to excellent intracellular stability and traceability within the complex biological environment. A magnetic stimulus (smaller than fN forces) results in the quick and reversible redistribution of the MNPs. The obtained data suggest that semisynthetic ferritin MNPs are highly versatile nanoagents and promising candidates for theranostic or (bio-)nanotechnological applications.

High-pressure torsion of powder blends is used as an unconventional process route for the production of textured magnetic SmCo5-20 wt% Sn nanocomposites. The use of powders as precursors which get consolidated by the process, enables to overcome limitations of conventional sintering based routes, as the hard magnetic phase and the grain boundary phase can be freely selected. Simultaneously, the microstructure can be adjusted by different process parameters. In this work, Sn is used as binder phase to magnetically decouple the SmCo5 particles and thus enhance magnetic hardening effects while simultaneously it is not soluble within the SmCo5 phase, thus preventing or rather delaying mechanical alloying effects. The influence of different number of rotations on the microstructure and the accompanied magnetic properties is investigated. With increasing number of rotations and thus strain, a grain refinement up to the single magnetic domain particle size (similar to 1 mu m) is observed, which leads to a magnetic hardening up to a coercivity of mu H-0(c) = 1.77 T and the formation of a macroscopic texture. With further refinement the coercivity decreases again. This decrease is ascribed to amorphization and intermixing of the two constituent phases SmCo5 and Sn as observed by transmission electron microscopy and atom probe tomography investigations. The detailed analyses of the interphases and their effect on the magnetic properties can be used to develop optimization strategies for the production of magnetic nanocomposites by high-pressure torsion.

Magnetic high-entropy alloys (HEAs) with their unusual blend of long-range magnetic order and exceptional mechanical properties are beneficial for the development of next-generation spintronic devices that can withstand extreme conditions. Developing room-temperature magnetic HEAs and understanding the link among their magnetic, electronic, and mechanical properties are crucial. Here, we introduce nanocrystalline CoCrFeNiGa as a room-temperature bulk magnetic HEA candidate based on 3d-transition metals and elucidate its magnetic and electronic properties. Structural characterization reveals the existence of mixed BCC and FCC phases with a crystallite size of ∼51 nm. CoCrFeNiGa shows a high Curie temperature (TC) of ∼872 K and soft magnetic behavior with minimal coercivity. We also observed spin freezing below 60 K, likely due to competing magnetic interactions among its 3d-transition metals. Electrical resistivity measurements confirm metallic behavior with magnon contributions below 50 K. Interestingly, CoCrFeNiGa exhibits a large anomalous Hall effect (AHE), with an anomalous Hall conductivity of ∼603 S·cm-1 at 5 K and ∼144 S·cm-1 at 300 K, persisting despite inherent disorder. This AHE is primarily attributed to an intrinsic mechanism. The combination of the above room-temperature magnetic order, soft magnetic properties, a large intrinsic AHE, and competing magnetic interactions positions CoCrFeNiGa as a prospective candidate for the development of next-generation robust spintronic devices and architectures using nanocrystalline magnetic HEAs, which are resilient under demanding conditions.

Magnetic phase transitions at the Curie temperature are essential for applications like magnetocaloric refrigeration, magnetic sensors, and actuators, but the reliance on costly, scarce rare-earth materials limits sustainability. Developing affordable, rare-earth-free materials with tunable magnetic properties and scalable miniaturization methods is vital for advancing technology. We present a comprehensive synthesis approach for rare-earth-free compositionally complex alloys (CCAs) with magnetic phase transitions, spanning from bulk materials to nanoparticles. Specifically, we investigate Mn22.3Fe22.2Ni22.2Ge16.65Si16.65 (Ge-based CCA) and Mn0.5Fe0.5NiSi0.93Al0.07 (Al-based CCA). The bulk materials are prepared by ball milling and spark plasma sintering or powder pressing and sintering. Nanoparticles (NPs) from the bulk materials are synthesized by pulsed laser ablation in liquid. Magnetization measurements confirm a ferromagnetic-to-paramagnetic phase transition in bulk alloys, with T c = 179 K for Ge-based CCA and T c = 263 K for Al-based CCA. At the nanoscale, both Ge- and Al-based NPs exhibit superparamagnetic behaviour, with blocking temperatures of T B ≈ 120 K for Ge-based NPs (x c = 13.4 ± 15.5 nm, average particle size) and T B ≈ 100 K for Al-based NPs (x c = 18.4 ± 9.1 nm, average particle size), demonstrating the intrinsic superparamagnetic nature of NPs. While the Ge-based CCA demonstrates almost twice the saturation magnetization (M s) and ≈20% lower hysteresis (H c) in bulk form, the Al-based CCA exhibits comparable M s and ≈45% lower H c at the nanoscale at 5 K. These results indicate that the Al-based CCA is a promising, cost-effective alternative to Ge-based CCA at nanoscale, providing an economically viable and cost-effective alternative for nanoscale-based applications.