We report on the synthesis and characterization of M n 3 Ga thin films with controlled phase and orientation using DC magnetron sputtering. High-quality Mn-deficient hexagonal M n 3 Ga films with C-plane and M-plane orientations were achieved on various single-crystal substrates, and their structural properties were systematically investigated by x-ray diffraction. Magnetization, Hall effect, and neutron diffraction measurements confirm the formation of antiferromagnetic order below T N = 460 – 470 K and reveal its characteristic magnetic behavior. A sizable anomalous Hall effect is observed coexistent with weak net magnetization, consistent with the 120° noncollinear spin structure. The ability to tune both the crystal phase (hexagonal vs tetragonal) and orientation through composition and thermal treatment provides a platform for exploring the intrinsic magnetic and topological properties of M n 3 Ga , with promising implications for antiferromagnetic spintronic applications.

The name of one of the authors in the article by Colin et al. [Acta Cryst. (2025), B81, 37–46] is corrected.

Geometrical frustration in the face-centered-cubic (fcc) lattice presents a fundamental challenge in determining antiferromagnetic order, as the ground state is highly sensitive to subtle differences in competing magnetic interactions and structural symmetry. Here, we explore the magnetostructural interplay in two halide double perovskites, Cs2NaFeCl6 and Cs2AgFeCl6. Although both materials have a cubic structure at room temperature, neutron diffraction shows that they adopt different antiferromagnetic structures upon cooling. Cs2NaFeCl6 experiences a transition to an AFM-III order below 2.6 K, governed by J 1 and J 2 (first and second nearest-neighbor) magnetic exchange interactions. Cs2AgFeCl6, however, adopts an AFM-I order below 17 K, accompanied by a significant tetragonal distortion confirmed from both neutron diffraction and polarized Raman spectroscopy. Thermal expansion measurements reveal anomalous lattice expansion at the magnetic transitions in both compounds but are substantially stronger in Cs2AgFeCl6. Combining these findings with density functional theory (DFT) studies, we conclude that the strength of magnetoelastic coupling dictates the magnetic ground state. A strong J 1 in Cs2AgFeCl6 induces a large tetragonal lattice distortion, relieving magnetic frustration and stabilizing the AFM-I phase. In contrast, weaker magnetoelastic coupling in Cs2NaFeCl6 causes minimal distortion, favoring the AFM-III phase via the J 1-J 2 mechanism. Our findings show that magnetic interactions can be a primary driving force for structural phase transitions in these materials, while the strong structural distortion could determine the selection of magnetic ground-state ordering.

We report a comprehensive study of spin dynamics in the (Mo_{2/3}Tb_{1/3})_{2}AlC i-MAX compound using ac susceptibility measurements across a range of magnetic fields. Unique behaviors were observed, including spin dynamics in the kHz range between μ_{0}H≈0.2T−6T, indicating a nontrivial superparamagnetic state, suggesting that the compound acts as a transitional system within the i-MAX family, bridging stable spin-dynamic materials and fluctuation-dominated ones. Field- and frequency-dependent magnetic phase transitions, coupled with relaxation behaviors, reveal complex interactions between spin density waves and superparamagnetic components. These findings, corroborated by μSR studies, deepen our understanding of magnetic phase diagrams and field-induced phenomena in i-MAX systems, laying the groundwork for further exploration of their unique properties and applications.

Rare-earth-based-in-plane-ordered MAX phases (R-i-MAX) are a family of nano-laminated compounds with chemical formula (Mo2/3R1/3)2AlC that have attracted interest as potential precursors for magnetic twodimensional (2D) derivatives. Experimental investigations of the magnetic properties of these materials have revealed complicated magnetic phase diagrams with multiple magnetic phase transitions as a function of temperature and external field, commensurate and incommensurate magnetic ordering, as well as fluctuations of the magnetic moments when rare-earths heavier than Gd are introduced. In this work, the magnetic exchange interactions of R-i-MAX phases, where R = Nd, Sm, Gd, Tb, Dy, Ho, and Er are calculated using density functional theory and are measured experimentally using magnetic diffuse neutron scattering measurements on powder samples with R =Tb and Er. Good quantitative agreement is found between the measured and calculated exchange interactions, as well as between the observed and calculated relative magnetic ordering temperatures. The strongest interaction is found to be for rare-earths separated by the Al layer, with much weaker interactions in the carbide layer. These results may have significant implications on the existence of magnetism in the two-dimensional derivatives of the MAX phases. This study is an initial step in developing a computational framework for the prediction and optimization of potential 2D magnets in the R-i-MAX family of compounds.

The magnetic structures of the Ho-based i-MAX phase (Mo 2/3 Ho 1/3 ) 2 GaC were studied with neutron powder diffraction at low temperature. (Mo 2/3 Ho 1/3 ) 2 GaC crystallizes in the orthorhombic space group Cmcm . The material undergoes two successive antiferromagnetic transitions at T N1 = 10 K and T N2 = 7.2 K. The magnetic structure below T N1 is incommensurate with the propagation vector k 1 = (0, k y , 0) with k y = 0.696 (1) at 9 K. For the analysis of the magnetic structure, a group-theoretical approach based on the space group of the nuclear structure and its subgroups was employed. A model in the (3+1)D superspace group Cmcm .1′(0β0) s 0 ss yielded the most accurate results in neutron powder diffraction refinements. The determined structure was found to be an incommensurate longitudinal amplitude-modulated magnetic structure. Below T N2 , additional magnetic satellites develop. They could be indexed by a propagation vector k 2 = (τ x , 0, 0) with the τ x value increasing below T N2 until it stabilizes at approximately 3 K at 0.075. A magnetic structure determination considering two propagation vectors k 1 and k 2 was carried out using the superspace formalism by building the corresponding (3+2)D model. The determination was based on the observation that the additional magnetic peaks emerge exclusively in the vicinity of the incommensurate magnetic peaks with propagation vector k 1 , and not in the vicinity of nuclear peaks. This indicates that only mixed-index reflections were observed, and not reflections purely related to k 2 . The magnetic superspace group (MSSG) that was determined is Amma .1′ (0,β,0)00 s 0 (0,0,γ) ss 0 s . The structure can be described as a longitudinal amplitude-modulated structure, which itself is amplitude-modulated in a perpendicular direction. This represents a very unusual case of a 2- k magnetic structure with no symmetry relation between the propagation vectors.

TiB2 is well established as a superhard coating material with a high melting point and a low friction coefficient. However, its brittle nature limits its utilization in arc evaporation, a commonly used technique in the thin film industry. In this work, we report the use of circular TiB2 cathodes, 100 mm in diameter, for thin film deposition in a DC vacuum arc system utilizing an industrial arc plasma source. We demonstrate that arcing from the TiB2 cathode is stable, and at a distance of 20 cm from the cathode surface, a deposition rate of 100 nm/min on a Si substrate heated to 500 degrees C is achieved. Notably, the resulting film composition exhibits a B/Ti ratio of approximately 1.2, with a measured hardness of around 34 GPa. By evaluating the plasma ion composition and analyzing the deposited films at varying distances and angles from the cathode surface normal, a spatial dependence of the boron content was observed. Shifting the substrate position 10 cm off-axis from the cathode center increased the B/Ti ratio in the film to approximately 1.5, resulting in a hardness of up to similar to 38 GPa. Plasma diagnostics confirmed a higher boron ion content at larger angles from the surface normal. These results demonstrate the high potential of industrial cathodic arc systems as efficient and practical methods for the synthesis of metal boride coatings.

MAX phases are a family of atomically laminated materials with various potential applications. Mn2GaC is a prototype magnetic MAX phase, where complex magnetic behaviour arises due to competing interactions. We have resolved the room temperature magnetic structure of Mn2GaC by neutron diffraction from single-crystal thin films and we propose a magnetic model for the low temperature phase. It orders in a helical structure, with a rotation angle that changes gradually between 120° and 90° depending on temperature.

We uncover a high-field magnetic phase in i-MAX compounds exhibiting a canted antiferromagnetic order with unprecedented properties, revealed through NMR and AC susceptibility. Intriguingly, as the atomic number of rare earth increases, the transition field of this canted antiferromagnetic phase grows at the expense of the lower-field antiferromagnetic state. Our findings point to the complexity of the magnetic structure in i-MAX compounds, demonstrating a nontrivial evolution of their phase diagram while increasing both the atomic number of the rare-earth element and the external field.

The recent discovery of chemical ordering in quaternary borides offers new ways of exploring properties and functionalities of these laminated phases. Here, we have synthesized and investigated chemical ordering of the laminated Mo4MnSiB2 (T2) phase, thereby introducing a magnetic element into the family of materials coined o-MAB phases. By X-ray diffraction and scanning transmission electron microscopy, we provide evidence for out-of-plane chemical ordering of Mo and Mn, with Mo occupying the 16l site and Mn preferentially residing in the 4c site. Mn and B constitute quasi-two-dimensional layers in the laminated material. We have therefore also studied the magnetic properties by magnetometry, and no sign of long-range magnetic order is observed. An initial assessment of the magnetic ordering has been further studied by density functional theory (DFT) calculations, and while we find an antiferromagnetic configuration to be the most stable one, ferromagnetic ordering is very close in energy.

MAX/MAB phases are a series of non-van der Waals ternary layered ceramic materials with a hexagonal structure, rich in elemental composition and crystal structure, and embody physical properties of both ceramics and metals. They exhibit great potential for applications in extreme environments such as high temperature, strong corrosion, and irradiation. In recent years, two-dimensional (2D) materials derived from the MAX/MAB phase (MXene and MBene) have attracted enormous interest in the fields of materials physics and materials chemistry and become a new 2D van der Waals material after graphene and transition metal dichalcogenides. Therefore, structural modulation of MAX/MAB phase materials is essential for understanding the intrinsic properties of this broad class of layered ceramics and for investigating the functional properties of their derived structures. In this paper, we summarize new developments in MAX/MAB phases in recent years in terms of structural modulation, theoretical calculation, and fundamental application research and provide an outlook on the key challenges and prospects for the future development of these layered materials.

High-entropy (HE) ceramics, by analogy with HE metallic alloys, are an emerging family of multielemental solid solutions. These materials offer a large compositional space, with a corresponding large range of properties. Here, we report the experimental realization of a 3D HE MAX phase, Ti1,0V0.7Cr0.05Nb1.0Ta1.0AlC3, and a corresponding 2D HE MXene in the form of freestanding flakes of average composition Ti1.1V0.7CrxNb1.0Ta0.6C3Tz (T-z = -F, -O, -OH), as produced by selective removal of AI from the HE MAX phase in aqueous hydrofluoric acid (HF). Initial tests on HE MXene "paper" electrodes show their high potential as electrode materials in supercapacitors through volumetric and gravimetric capacitances of 1688 F/cm(3) and 490 F/g, respectively, originating from a combination of diffusion- and surface-controlled charge storage processes. The introduction of the HE concept into the field of 2D materials suggests a wealth of future 2D materials and applications.

Recently, we presented a family of in-plane chemically ordered transition metal borides of the general formula (M-2/3'M-1/3")(2)AlB2. Here, we investigate incorporation of magnetic rare earth (RE) elements into this structure by synthesis and analysis of Mo4/3RE2/3AlB2, where RE = Ho, Tb, and Er. The crystal structure is verified by X-ray diffraction and scanning transmission electron microscopy, while the composition is derived from energy dispersive X-ray analysis. Through magnetization measurements, we also show that Mo4/3Ho2/3AlB2 orders antiferromagnetically below 9 K. We suggest that (M-2/3'M-1/3")(2)AlB2 could potentially be a versatile platform for new magnetic materials, in 3D as well as 2D. [GARPHICS] IMPACT STATEMENT This paper introduces magnetic elements to i-MAB phases family with a formula of Mo4/3RE2/3AlB2 (RE = Ho, Er, and Tb), which opens a venue for further exploration of chemically ordered magnetic materials.

We report the results of magnetization, heat capacity, and neutron diffraction measurements on (Mo2/3RE1/3)(2)AlC with RE = Dy and Tb. Temperature and field-dependent magnetization as well as heat capacity were measured on a powder sample and on a single crystal allowing the construction of the magnetic field-temperature phase diagram. To study the magnetic structure of each magnetic phase, we applied neutron diffraction in a magnetic field up to 6 T. For (Mo2/3Dy1/3)(2)AlC in zero field, a spin density wave is stabilized at 16 K, with antiferromagnetic ordering at 13 K. Furthermore, we identify the coexistence of ferromagnetic and antiferromagnetic phases induced by magnetic fields for both RE = Tb and Dy. The origin of the field induced phases is resulting from the competing ferromagnetic and antiferromagnetic interactions.

Exploratory theoretical predictions in uncharted structural and compositional space are integral to materials discoveries. Inspired by M 5 SiB 2 (T2) phases, the finding of a family of laminated quaternary metal borides, M ′ 4 M ″SiB 2 , with out‐of‐plane chemical order is reported here. 11 chemically ordered phases as well as 40 solid solutions, introducing four elements previously not observed in these borides are predicted. The predictions are experimentally verified for Ti 4 MoSiB 2 , establishing Ti as part of the T2 boride compositional space. Chemical exfoliation of Ti 4 MoSiB 2 and select removal of Si and MoB 2 sub‐layers is validated by derivation of a 2D material, TiO x Cl y , of high yield and in the form of delaminated sheets. These sheets have an experimentally determined direct band gap of ≈4.1 eV, and display characteristics suitable for supercapacitor applications. The results take the concept of chemical exfoliation beyond currently available 2D materials, and expands the envelope of 3D and 2D candidates, and their applications.

The integration and interaction of vision, touch, hearing, smell, and taste in the human multisensory neural network facilitate high-level cognitive functionalities, such as crossmodal integration, recognition, and imagination for accurate evaluation and comprehensive understanding of the multimodal world. Here, we report a bioinspired multisensory neural network that integrates artificial optic, afferent, auditory, and simulated olfactory and gustatory sensory nerves. With distributed multiple sensors and biomimetic hierarchical architectures, our system can not only sense, process, and memorize multimodal information, but also fuse multisensory data at hardware and software level. Using crossmodal learning, the system is capable of crossmodally recognizing and imagining multimodal information, such as visualizing alphabet letters upon handwritten input, recognizing multimodal visual/smell/taste information or imagining a never-seen picture when hearing its description. Our multisensory neural network provides a promising approach towards robotic sensing and perception.

We report muon spin rotation (μSR) and neutron diffraction on the rare-earth based magnets (Mo_2/3RE_1/3)_2AlC, also predicted as parent materials for 2D derivatives, where RE = Nd, Gd (only (μSR), Tb, Dy, Ho and Er. By crossing information between the two techniques, we determine the magnetic moment (m), structure, and dynamic properties of all compounds. We find that only for RE = Nd and Gd the moments are frozen on a microsecond time scale. Out of these two, the most promising compound for a potential 2D high (m) magnet is the Gd variant, since the parent crystals are pristine with m = 6.5 ± 0.5 μ_B, Néel temperature of 29 ± 1 K, and the magnetic anisotropy between in and out of plane coupling is smaller than 10^-8. This result suggests that magnetic ordering in the Gd variant is dominated by in-plane magnetic interactions and should therefore remain stable if exfoliated into 2D sheets.

Extensive research has been invested in two-dimensional (2D) materials, typically synthesized by exfoliation of van der Waals solids. One exception is MXenes, derived from the etching of constituent layers in transition metal carbides and nitrides. We report the experimental realization of boridene in the form of single-layer 2D molybdenum boride sheets with ordered metal vacancies, Mo4/3B2-xTz (where Tz is fluorine, oxygen, or hydroxide surface terminations), produced by selective etching of aluminum and yttrium or scandium atoms from 3D in-plane chemically ordered (Mo2/3Y1/3)2AlB2 and (Mo2/3Sc1/3)2AlB2 in aqueous hydrofluoric acid. The discovery of a 2D transition metal boride suggests a wealth of future 2D materials that can be obtained through the chemical exfoliation of laminated compounds.

We report muon spin rotation (mu SR) and neutron diffraction on the rare-earth-based magnets (Mo2/3RE1/3)2AlC, also predicted as parent materials for two-dimensional (2D) derivatives, where the rare earth (RE) = Nd, Gd (only mu SR), Tb, Dy, Ho, and Er. By crossing information between the two techniques, we determine the magnetic moment (m), structure, and dynamic properties of all compounds. We find that only for RE = Nd and Gd the moments are frozen on a microsecond timescale. Out of these two, the most promising compound for a potential 2D high m magnet is the Gd variant, since the parent crystals are pristine with m = 6.5 +/- 0.5 mu B, Neel temperature of 29 +/- 1 K, and the magnetic anisotropy between out-of- and in-plane coupling is smaller than 10-8. This result suggests that magnetic ordering in the Gd variant is dominated by in-plane magnetic interactions and should therefore remain stable when exfoliated into 2D sheets.