van der Waals metal-organic magnets (vdW MOMs) offer the possibility of realizing a wide range of magnetic functionalities not possible in inorganic vdW magnets. In particular, their modularity allows for specific control over ligand-mediated superexchange and hence their ground states. We report a new vdW MOM, CrCl2(btd) (btd = 2,1,3-benzothiadiazole), assembled from a high-energy early transition metal and a redox-active ligand, which leads to a small charge-transfer gap. We solve the structure using a combination of powder neutron diffraction and single-crystal electron diffraction, showing that this material contains Cr2+btd0. Magnetometry, neutron diffraction, and inelastic neutron scattering measurements allow us to quantitatively determine the magnetic properties of this vdW magnet, showing it is a collinear rectangular antiferromagnet with small easy-axis anisotropy (J Cl = -15.31(5) K, J btd = -6.96(10) K, D = -2.0(2) K). Critically, we find that the superexchange through btd, with a low-lying LUMO, is significantly stronger than in the CrCl2(pym) (pym = pyrimidine) analogue (J pym = +1.2(2) K), demonstrating that exchange can be enhanced by potentially redox-active ligands without actual electron-transfer onto ligands. This work provides a route toward vdW antiferromagnetic MOMs with strong magnetic superexchange.

We report a comprehensive investigation of the physical properties of single crystals of Dirac semimetal EuAuBi, using neutron diffraction, magnetization, electrical transport, and specific heat measurements. EuAuBi crystallizes in a hexagonal structure with space group P63mc (no. 186). First-principles calculations using density functional theory characterize it as a Dirac semimetal, with a notable band crossing in proximity to the Fermi level (EF) along the P-A direction. The crystal exhibits three distinct magnetic phases at 4 K (TN1), 3.5 K (TN2), and 2.8 K (TN3) as observed from magnetic and specific heat measurements. However, zero-field neutron diffraction resolves only two magnetic phases: a commensurate antiferromagnetic phase and a canted antiferromagnetic phase. Field-dependent ac and dc magnetization measurements uncover field-induced nontrivial spin textures in the magnetic field range 1.5 to 3 T, manifested as a tilted plateau in the magnetization curves. The interplay between conduction carriers and these spin textures is further evidenced by unique features in the magnetic field-dependent longitudinal resistivity. Finally, we present a comprehensive magnetic phase diagram of EuAuBi, highlighting diverse spin alignments present in the material. EuAuBi thus emerges as a rare material system in which both momentum-space and real-space Berry curvature effects may coexist, providing a unique opportunity to investigate their interplay.

The development of diverse battery chemistries demands advanced diagnostic techniques to study them. Neutron diffraction, which is sensitive to light elements and capable of distinguishing transition metals with similar electronic configurations, is well-suited to probe crystallographic transformations in battery materials and their degradation pathways. Yet its use has been limited by compromised data quality, low time resolution, and the absence of resource-efficient, reproducible, benchmarked electrochemical cells. Here, using the high-resolution cold-neutron diffractometer WISH, we demonstrate operando neutron diffraction studies of standard laboratory-scale single-layer pouch cells without build modifications, electrolyte deuteration, or isotope enrichment of the electrodes, under practical cycling conditions. This expands the battery diagnostic toolkit beyond X-rays and enables academic exploration of both established and emerging technologies, especially lithium-metal, anode-less, and lithium-sulfur batteries.

NaNiO2 is a promising cathode material for sodium-ion batteries due to its high theoretical capacity of 235.8 mAh.g-1. However, as with many Na-ion cathode materials, a series of poorly understood phase transitions occur on electrochemical cycling, inducing volume mismatch-based stress/strain, resulting in particle cracking, electrochemically disconnected particles and, therefore, irreversible capacity loss. This behavior is one key obstacle to developing long-lasting, high-performance Na-ion batteries. Although the series of phases that form as NaxNiO2 is electrochemically cycled have been previously identified, their structures remained unsolved, limiting our ability to understand and control the phase transition behavior. Here, we report structural solutions based on Rietveld refinement against high-resolution synchrotron x-ray diffraction (SXRD) and neutron powder diffraction (NPD) for the phases obtained on desodiation: P″3-Na1/2NiO2, O″3-Na2/5NiO2, and O‴3-Na1/3NiO2. Each phase contains a unique Na+/vacancy ordering, minimizing intralayer electrostatic repulsions between Na+ ions, and Nix+-charge ordering decreasing interlayer repulsions through the location of lower valence Nix+ nearer to vacancies. Using these structures, we conduct sequential Rietveld refinement against operando SXRD data, which supports prior identification of a transient P‴3-Na1/2<x<2/3NiO2 phase, not isolable ex situ. Operando data also identify the presence of a solid-solution phase O″3δ-Na1/3<x<2/5NiO2 and second-order behavior of the O″3-Na2/5NiO2 → O‴3-Na1/3NiO2 phase transition at the top of charge. This work provides unprecedented insight into structural evolution during electrochemical cycling in Ni-rich Na cathodes (and likely Li analogues), paving the way toward rational doping regimes designed to disrupt degradation-inducing phase transitions, increasing capacity and cycle lifetime, thus improving the performance of Co-free Na and Li cathodes.

We realise the first ultralow-field Bose-Einstein condensation of triplons in a spin-ladder magnet, uncovering a quantum critical point at only μ_0 H_c1=0.17 T in Henmilite (Ca_2Cu(OH)_4[B(OH)_4]_2). Unlike dimer magnets, a ladder retains extended one-dimensional correlations in its gapped parent state, making this limit strongly fluctuation dominated. Thermodynamic, magnetoelastic, μSR, and neutron-diffraction measurements overturn the previous assignment of zero-field antiferromagnetic order, establishing a quantum-disordered coupled-ladder parent state with persistent low-energy dynamics. The weak low-temperature anomaly instead marks a gap-controlled crossover from the correlated ladder regime into the activated quantum-disordered state. These measurements further reveal an exceptionally asymmetric ordered dome extending to μ_0 H_c2≃ 8.2 T. Quantum Monte Carlo simulations for the relevant spin Hamiltonian place Henmilite just on the gapped side of the zero-field ladder-ordering instability, naturally accounting for the strong separation between the exchange and residual-gap scales and the tiny critical field. Our findings extend ultralow-field triplon condensation beyond the dimer paradigm and establish Henmilite as a platform for controlled tuning across quantum criticality in a fluctuation-dominated spin ladder.

The spin supersolid-a magnetic analogue of the supersolid that simultaneously exhibits solid and superfluid orders-has emerged as a promising sub-Kelvin refrigerant with strong low-energy fluctuations and associated entropic effects1. However, the stringent prerequisites have so far confined its presence to certain magnetic insulators. Here we report the discovery of a metallic spin supersolid in a rare-earth compound EuCo2Al9 (ECA), which is a good metal with excellent electrical and thermal conductivity. The high-spin Eu2+ ions form a three-dimensional lattice with stacked triangular layers, in which the spin-supersolid state is stabilized through a mechanism involving both Ruderman-Kittel-Kasuya-Yosida (RKKY) and dipolar couplings. Neutron diffraction shows microscopic evidence of spin supersolidity, demonstrating the coexistence of out-of-plane and in-plane spin orders in this alloy. Our RKKY-dipolar model successfully captures the metallic spin-supersolid Y and V phases in ECA, along with the 1/3 magnetization plateau. The observed nonclassical magnetization behaviours within these phases point to significant quantum fluctuations, probably enhanced by the conduction electrons. The resistivity measurements provide a transport probe for the spin-supersolid transitions, because of scattering of conduction electrons from local moments. Through the adiabatic demagnetization process, ECA achieves ultralow cooling to 106 mK, exhibiting a giant magnetocaloric effect that manifests sharp anomalies in the magnetic Grüneisen ratio. ECA emerges as one of the first metallic spin supersolids, combining low cooling temperature, large magnetic entropy and ultrahigh thermal conductivity for high-performance sub-Kelvin refrigeration.

Neutron diffraction is the primary technique to study magnetic long-range ordering in crystalline materials. Historically this method required a large sample volume, making it unsuitable for application to thin film samples. In this perspective paper, we would like to bring the thin film community's attention to new opportunities and capabilities offered by the current state of the art instrumentation. In particular, we focus on recent developments on the time-of-flight cold neutron diffractometer WISH located at the ISIS neutron and muon source. Starting from the description of a typical thin film neutron diffraction experiment, we highlight the advantages provided by the Laue time-of-flight technique with some key examples taken from recent literature. These examples represent case studies of functional materials where neutron diffraction has provided crucial information about their magnetic structures and domain patterns. Finally we discuss some future opportunities and upgrades which will further push the limit of the neutron diffraction technique in the field of epitaxial magnetic thin films and heterostructures.

NaNiO 2 is a promising cathode material for sodium-ion batteries due to its high theoretical capacity of 235.8 mAh.g -1 . However, as with many Na-ion cathode materials, a series of poorly understood phase transitions occur on electrochemical cycling, inducing volume mismatch-based stress/strain and resulting in particle cracking, electrochemically disconnected particles, and therefore, irreversible capacity loss. This behaviour is one key obstacle in the development of long-lasting, high-performance Na-ion batteries. Although the series of phases that form as Na x NiO 2 is electrochemically cycled have been previously identified, their structures remained unsolved, limiting our ability to understand and control the phase transition behaviour. Following our recent structure solution of the first desodiated phase Pʹ3-Na 2/3 NiO 2 , we now report structural solutions based on Rietveld refinement of high-resolution synchrotron X-ray diffraction (SXRD) and neutron powder diffraction (NPD) for the remaining phases obtained on desodiation: Pʹʹ3-Na 1/2 NiO 2 , Oʹʹ3-Na 2/5 NiO 2 , and Oʹʹʹ3-Na 1/3 NiO 2 . Each phase contains a unique Na + /vacancy ordering, which minimises intralayer electrostatic repulsions between Na + ions, and Ni x+ -charge ordering which reduces interlayer repulsions through location of lower valence Ni x+ nearer to vacancies. Using these structures, we conduct sequential Rietveld refinement of operando SXRD data, which supports prior identification of a transient Pʹʹʹ3-Na 1/2 NiO 2 phase, which is not isolable ex situ. Our operando data also identify the presence of a solid-solution phase Oʹʹ3 δ -Na 1/3 NiO 2 and second-order behaviour of the Oʹʹ3-Na 2/5 NiO 2 -> Oʹʹʹ3-Na 1/3 NiO 2 phase transition at the top of charge. This work provides unprecedented insight into structural evolution during electrochemical cycling in Ni-rich Na cathodes (and likely, Li analogues), paving the way towards rational doping regimes designed to disrupt degradation-inducing phase transitions to increase capacity and cycle lifetime, and improve performance of Co-free Na and Li cathodes.

We demonstrate control of helimagnetic order in biaxially strained SrFeO3 thin films using neutron diffraction and resonant soft x-ray scattering. SrFeO3, a negative charge-transfer oxide, exhibits a complex magnetic phase diagram that includes multi-q spin structures. Tensile epitaxial strain produces a pronounced shortening of the helimagnetic ordering length and a tilting of the magnetic ordering vector. We interpret this behavior in terms of chemical expansion: lattice dilation under tensile strain lowers the energetic cost of oxygen vacancies, leading to an expanded unit cell that modifies Fe-O hybridization and enhances superexchange relative to double exchange. These results reveal how epitaxial strain can indirectly tune helimagnetism through defect-driven chemical expansion, highlighting the strong coupling between lattice, chemistry, and magnetic order in transition-metal oxides. Our findings establish chemical expansion as an effective mechanism for engineering complex magnetic textures in oxide thin films, with implications for spintronic, magnonic, and quantum information applications.

Magnetic ordering in quasicrystals has recently emerged as a fertile ground for discovering unconventional magnetic states beyond the framework of periodic crystals. However, elucidating the microscopic origin of such states remains challenging due to the intrinsic aperiodicity of quasicrystals. Here, we address this issue by investigating the prototypical Tsai-type quasicrystal approximant Cd6Tb, which preserves the essential local geometry and connectivity of icosahedral quasicrystals while allowing detailed structural and magnetic characterization due to its translational periodicity. Using neutron diffraction measurements, we find a noncoplanar multi-k magnetic ground state composed of Ising-like Tb moments arranged on a network of corner-sharing octahedra, the ingredients required to host octahedral spin-ice physics. Remarkably, only one third of the Tb moments develop long-range magnetic order, whereas the remaining moments display strongly reduced static order accompanied by persistent spin dynamics on microsecond timescales, as evidenced by muon spin rotation. This coexistence of ordered and fluctuating moments constitutes a potential realization of magnetic fragmentation - a key prediction of octahedral spin-ice physics - in a quasicrystal-related material.

GdCo2B2 is a member of the ThCr2Si2 family of compounds which exhibits good magnetocaloric properties associated with antiferromagnetic orderings in the temperature range for hydrogen liquefaction applications. As antiferromagnetic compounds typically do not exhibit a large magnetocaloric effect, understanding the magnetic orderings in GdCo2B2 could help uncover more magnetocaloric compounds that rely on antiferromagnetic ordering. GdCo2B2 exhibits four antiferromagnetic phase transitions at 22 K, 18.5 K, 13 K, and 7 K. Due to the difficulty of conducting neutron diffraction measurements on compounds containing affordable natural Gd, the microscopic magnetic structures have so far not been investigated. In this study, by using high energy neutrons and devising special sample preparations for lower energy neutrons, powder neutron diffraction patterns of GdCo2B2 have successfully been measured. A long-period incommensurate magnetic ordering with k1 = (0.0531 0 0) was seen at 20 K. The propagation vector of the incommensurate structure shifted to k1 = (0.071 0 0) at 16 K, and an additional k = (0 0 0) ferromagnetic component was observed. At 10 K, two incommensurate propagation vectors of k1 = (0.0731 0 0) and k2 = (0.0731 0.0731 0), which shifted to k1 = (0.0741 0 0) and k2 = (0.0741 0.0741 0) at 6 K, were observed to coexist. By considering only the k1-modulation, two possible magnetic structures below 10 K are reported to describe the data, either ac-cycloid structure with constant moment at each Gd site or ellipsoidal ab-cycloid structure. Exchange interaction energy calculations indicated that the long-period antiferromagnetic ordering in GdCo2B2 is energetically close to the ferromagnetic state due to the strong competition between ferromagnetic and antiferromagnetic exchange interactions, which plays an essential role for the emergence of the large magnetocaloric effect in GdCo2B2.

We investigated the structural and magnetic properties of single-crystalline VCl3, a newly synthesized member of the vanadium trihalide family. High-quality single crystals were grown by the chemical vapor transport method, and their behavior was characterized using neutron diffraction and thermodynamic measurements. We show that VCl3 crystallizes in the BiI3-type structure at room temperature and undergoes a structural phase transition at TS = 103.7(5) K that lowers the lattice symmetry, followed by a zigzag antiferromagnetic order with a propagation vector k = (0, 0.5, 1) below TN = 21.8(1) K. Neutron diffraction experiments indicate that the ordered moments are canted by approximately 21 degrees away from the c axis toward the a axis, yielding a total moment of approximately 1.09(2)mu B/V3+. Field-dependent magnetization along the c axis exhibits a half magnetization plateau, indicative of a field-stabilized fractional state. These results establish VCl3 as a new platform for exploring structural transitions, anisotropic magnetism, and field-induced phases in vanadium-based honeycomb magnets.

The conversion of high-density polyethylene wastes to aromatic feedstocks in noble-metal-free systems poses a significant challenge. Here, we report a steam-assisted synthesised zeolite (SA-HZSM-5) that can promote the conversion of high-density polyethylene to aromatics, achieving simultaneously high conversion and selectivity (85.4% and 49.2%, respectively) at 260 °C, outperforming noble metal-based catalysts, such as Ru-HZSM-5, under the same conditions. The produced aromatics predominantly consist of valuable monocyclic aromatics (circa 85%). The steam-assisted synthetic method endows a specific distribution of Lewis and Brønsted acid sites in SA-HZSM-5. In situ neutron diffraction and infrared spectroscopy, coupled with modelling, reveal a dual-site adsorption mechanism of mono-olefins intermediates, facilitating their transformation into dienes with suitable spaced double bonds, a feature that is crucial for the sequential cyclisation and dehydroaromatisation into aromatic compounds. This study underscores the potential of hierarchical zeolite materials for efficient upcycling of plastic wastes into chemical feedstocks.

Uniaxial stress is a promising method to tune magnetic frustration, allowing its effects to be studied in a precise way. In this work, uniaxial stress is applied to the triangular-lattice antiferromagnet PdCrO2. The Cr-Cr magnetic interaction is very sensitive to interatomic separation, so laboratory-achievable stress can induce substantial changes in magnetic structure. Results from three types of measurement are presented: x-ray diffraction, the stress-strain relationship, and neutron diffraction. The combined data show that the elastic moduli of PdCrO2are strongly affected by stress-induced changes in magnetic structure. A new, first-order stress-induced magnetic transition is observed, at which the lattice constant shrinks by 0.21%. The lattice stiffens dramatically across this transition: the Young's modulus increases by≈80GPa, and the Poisson ratio falls from≈1to≈0.4. This stiffening indicates that the magnetic order 'locks,' that is, becomes insensitive to lattice strain. This locking might occur because the new stress-induced magnetic order nests the Fermi surface of the Pd sheets. Other frustrated magnets, including candidate spin liquids, may show similarly strong coupling between magnetic and elastic degrees of freedom.

The discovery of the intrinsic anomalous Hall effect (AHE) in noncollinear antiferromagnets has opened a plethora of promising opportunities in antiferromagnetic devices. The key challenges limiting their full potential are (i) high-quality epitaxial thin-film growth and (ii) the understanding of Berry curvature and antiferromagnetic domain physics. Here, we focus on a noncollinear antiperovskite antiferromagnet Mn 3 NiN as a model system, successfully grown as a single-crystal epitaxial thin film. Combining multiple experiments supported by theoretical calculations, we probe the Berry curvature associated with antiferromagnetic Γ 4g domains in Mn 3 NiN and its strong connection to an AHE. We directly image the antiferromagnetic domains driving the intrinsic Berry curvature with high-resolution Sagnac MOKE (magneto-optical Kerr-effect) microscopy, controlling spatial distribution and dynamics by varying temperature and applied magnetic fields. Our findings provide critical advancement of the fundamental understanding and wide tunability of Berry curvature in noncollinear antiferromagnets important for realization in potential spintronic applications.

Frustrated Kondo lattices are ideal platforms for exploring unconventional forms of quantum criticality, as well as magnetism and other emergent phases. Here we report the magnetic properties of the candidate frustrated heavy fermion compound Ce_2PdSi_3, and map their evolution upon applying magnetic fields and hydrostatic pressure. We find that at ambient pressure Ce_2PdSi_3 exhibits two distinct magnetic phase transitions, a ferromagnetic-like transition at T_M1=3.8 K and an incommensurate antiferromagnetic transition at T_M2=2.9 K. Upon applying pressure, T_M1 is continuously suppressed and becomes undetectable above 4.2 GPa, whereas T_M2 increases and remains robust up to at least 7.5 GPa. The observed pressure evolution of magnetic order in Ce_2PdSi_3 suggests the presence of competing magnetic orders, and cannot be simply encapsulated by the Doniach phase diagram, motivating further investigations for its origin, including discerning the role of geometric frustration.

The prospect of merging the paradigms of geometric frustration on a triangular lattice and bond anisotropies in the strong spin-orbit coupling limit holds tremendous promise in the search for exotic quantum materials. Here we identify a new candidate system to realize such physics, the organic quantum antiferromagnet (CD3ND3)2NaRuCl6. We report a combination of thermodynamic, magneto-elastic and neutron scattering experiments on single-crystals to determine the phase diagram in axial magnetic fields H∥c and propose a minimal model Hamiltonian. (CD3ND3)2NaRuCl6 displays an ideal triangular arrangement of Ru3+ ions adopting the spin-orbital entangled j eff = 1/2 state. It hosts residual magnetic order below T N = 0.23 K and a highly unusual H - T phase diagram including three different incommensurate states. Spin-waves in the high-field polarized regime are described by a Heisenberg triangular lattice Hamiltonian with a potential sub-leading bond dependent anisotropy term J ±±. We argue that the multi-q ground state in zero magnetic field is a prime candidate for hosting the Z 2 vortex crystal proposed on the triangular Heisenberg-Kitaev model. (CD3ND3)2NaRuCl6 is the first member in an extended family of quantum triangular lattice magnets, providing a new playground to study the interplay of geometric frustration and spin-orbit effects.

ABSTRACT The spin cycloid characteristic of noncollinear antiferromagnets offers significant potential for energy‐efficient, magnon‐mediated spintronic applications. Multiferroic BiFeO 3 is among the most promising candidate materials because its antiferromagnetic order can be controlled by an electric field. However, in epitaxial BiFeO 3 thin films, substrate clamping and epitaxial strain modify the cycloidal magnetic structure while limiting efficient ferroelastic‐ferroelectric switching. Here, we show that strain‐released freestanding BiFeO 3 membranes overcome these limitations. Compared with substrate‐clamped epitaxial thin films, a 100‐nm‐thick freestanding membrane exhibits ≈50% faster electric‐field‐driven ferroelectric switching and a spatially uniform, bulk‐like single spin cycloid, as revealed by resonant elastic X‐ray scattering. In contrast, the epitaxial thin film exhibits an expanded cycloid periodicity and slower ferroelectric switching dynamics, reflecting the influence of substrate‐induced strain. Freestanding BiFeO 3 membranes therefore overcome substrate‐induced constraints by simultaneously restoring the intrinsic bulk‐like spin cycloid and enabling substantially faster ferroelectric switching. This combination of robust noncollinear antiferromagnetic order and efficient electric‐field switching establishes freestanding BiFeO 3 membranes as a promising magnetoelectric platform for low‐power magnonic and spintronic technologies, while enabling heterogeneous integration with Si‐based devices.

NiS2, a material long recognized for its non-collinear magnetic order and correlated insulating behavior, has until now been entirely overlooked as a potential host of topological phenomena. Bulk NiS2 is known to be a Mott or charge-transfer insulator, yet its surface exhibits anomalous finite conductivity of unclear origin. Additionally, a definitive consensus regarding its low-temperature magnetic transition remains elusive. In this work, we provide a unified explanation for both of these longstanding puzzles. First, we present a refined characterization of NiS2’s magnetic phases by proposing a novel ground state based on a rigorous symmetry analysis of high-resolution neutron scattering data. Second, through high-resolution scanning tunneling microscopy and spectroscopy (STM/STS), we reveal the presence of robust edge states on both Ni- and S-terminated surfaces, which persist even under applied magnetic fields. Using ab initio calculations combined with topological analysis, we attribute these edge states to obstructed atomic charges arising from the bulk’s obstructed nature. Altogether, this study not only sheds new light on the physics of NiS2, but also establishes a solid experimental and theoretical foundation for exploring the interplay between topology and electronic correlations. The interplay between topology and strong electronic correlations remains poorly understood in quantum materials. Here, the authors uncover unexpected edge states in the correlated insulator NiS2, offering a unified explanation for its origin and magnetic behavior in terms of obstructed Wannier charges.

Chromium antimonide has emerged as a key material platform for studying altermagnetism because of its simple binary composition, high Néel temperature, and semimetallic electronic structure. Here, we investigate electrical and thermal magnetotransport in single-crystalline CrSb using steady-and pulsed-magnetic fields up to 65 T, and complement these measurements with neutron diffraction and magnetization data. We confirm the compensated magnetic structure and observe a large nonsaturating magnetoresistance together with a pronounced nonlinear Hall response at low temperatures. Multicarrier modeling, supported by mobility-spectrum analysis, reveals coexisting electron- and hole-like charge carriers with mobilities up to 3000 cm2/Vs and shows that the number of transport channels that can be resolved strongly depends on the accessible magnetic-field range. Thermal-transport measurements further reveal a nonlinear thermal Hall response and a thermal conductivity substantially exceeding a simple Wiedemann-Franz law. The broadly similar field and temperature evolution of electrical and thermal transport point to a dominant electronic contribution, while the remaining deviations indicate additional heat-carrying channels.