Altermagnets are an emerging class of collinear antiferromagnets that exhibit unconventional spin-polarised electronic bands, potentially unlocking new functionalities that do not rely on spin-orbit coupling (SOC). Experimental signatures traditionally associated with spin polarisation, like X-ray magnetic circular dichroism (XMCD), are thus being used as a validation of altermagnetism. However, unlike altermagnetic spin-splitting, these responses require SOC and are not invariant under spin-space rotations. This brings into question the extent to which they can be considered direct signatures of altermagnetism. Here, we exploit the g-wave altermagnet α-Fe_2O_3 to demonstrate that XMCD is governed precisely by the spin-direction-induced symmetry breaking that altermagnetic spin groups are designed to ignore. Strikingly, the XMCD is highly anisotropic and is decoupled from the weak magnetic canting. We show that this anomalous XMCD can be described by on-site Faraday tensors capturing the locally uncompensated spin-orbital anisotropies - a scenario that can be applied to other altermagnets. Leveraging this, we reconstruct complete vectorial maps of nanoscale textures in α-Fe_2O_3 thin films, including domain walls and topological solitons, which are promising for building future spintronics and magnonics devices.

We report new developments on the $\mathbf{I 1 0}$ (BLADE) beamline of Diamond Light Source. The beamline exploits dichroism in X-ray scattering and absorption to investigate magnetic ordering and electronic structure of magnetic materials. Operating in soft X-ray region, it covers L-edges of the $3 d$ transition metals and the M-edge of $4 f$ rare earth elements. In this paper, we present an overview of the beamline, describe its two endstations along with recent upgrades.

A rare example of a seven-membered heterometallic ring [CrIII 6 CeIIIF7(O2CtBu)14(THF)2] (MeCN)2 (1) and five eight-membered heterometallic rings, [nPr2NH2][CrIII = Y, L = H2O, x = 1, 4, Ln = Gd, L = HO2CtBu, x = 1; 5, Ln = Tb, L = HO2CtBu, x = 1; 6, Ln = Yb, no L) have been synthesized and structurally characterized through X-ray diffraction. The structures consist of eight metals in an octagon, with Cr...Cr and Cr...Ln edges bridged by a fluoride and two carboxylates, while the Ln...Ln edges are bridged by a fluoride and three carboxylates. The magnetisation and susceptibility of these compounds were measured using SQUID magnetometry and electron paramagnetic resonance (EPR) spectroscopy. The magnetic data were fitted with antiferromagnetic exchange interactions between chromium(III) ions, which can be fitted in the {Cr6Y2} complex 3 and these parameters were then used to fit the magnetic properties of the {Cr6Gd2} complex 4 adding in exchange interactions between the CrIII and GdIII The magnetisation and susceptibility below 80 K of 1 and 2 were fitted on the basis of CASSCF-SO calculations at the CeIII site, and showed a weak ferromagnetic interaction between CrIII and CeIII. For 5 and 6 the magnetisation data was fitted by subtracting the data for 3 and treating the residual data as a {Tb2} and {Yb2} dimer respectively. The EPR spectra are rich, and for 3 can be modelled as due to S = 1 and S = 2 states of the {Cr6} chain. The spectra of 1 and 2 are similar, consistent with very weak interactions between the CeIII and the {Cr6} chain, while the spectra of 5 and 6 are different to that of 3, suggesting that the low temperature spectroscopy is due to a spin system in which the LnIII ions interact with the {Cr6} chain.

We report the dielectric and magnetic properties of epitaxial thin films of the high entropy oxide (HEO) perovskite Nd(Cr0.2Mn0.2Fe0.2Co0.2Ni0.2)O3, which orders magnetically below T mag approximate to 190 K. At T >> T mag, the dielectric response reveals a Debye-type frequency dependence with a zero-frequency dielectric constant of approximate to 230-250. The dc bias voltage loops of are reversible but exhibit three distinct peaks centred at zero and finite positive and negative voltage. We provide evidence that the zero-bias peak is governed by the oxygen sublattice while the finite bias peaks originate from cationic dipoles. The maximal response of the latter appears to be shifted to finite bias by a static uncompensated electric field due to a vertical gradient of the oxygen content. Below T mag, this anomalous dielectric response is strongly suppressed, presumably by magnetostriction that counteracts and freezes the ionic displacements. These findings indicate a unique correlation between configurational entropy, dielectric response, and magnetic properties. In combination with a large dielectric strength, it enables a non-hysteretic tuning of the dielectric response of magnetoelectronic devices with multiple parameters like temperature, electric, and magnetic field. This HEO is equally interesting for fundamental studies of competing electric and magnetic orders in strongly disordered materials.

Chemical disorder in compositionally complex perovskite oxides generates a broad distribution of exchange pathways and spin states, but the microscopic origin and spatial homogeneity of the resulting magnetic phases remain debated. Here, we tune the Mn fraction (x = 0.2-0.6) in epitaxial La(Cr, Mn, Fe, Co, Ni)O-3 thin films and resolve the coupled evolution of valence, spin state, and magnetism using element-specific x-ray absorption spectroscopy and x-ray magnetic circular dichroism (XMCD). Mn enrichment drives an internal redistribution of charge, in which Mn evolves toward a Mn3+-rich mixed valence, while Co converts from predominantly Co3+ to high-spin Co2+. This valence/spin-state coupling amplifies the Mn- and Co-derived ferromagnetic response by nearly an order of magnitude while increasing the magnetic onset temperature to at least 250 K, whereas Fe and Cr remain essentially trivalent with weak dichroism. Depth-resolved low-energy muon spin spectroscopy (LE-mu SR) shows magnetic homogeneity through the film thickness, with a secondary relaxation maximum near 25 K indicating a low-temperature dynamical crossover consistent with frustrated magnetism in a strongly disordered spin lattice.

Electrolyte stability governs the performance and lifetime of Li-ion batteries, yet a quantitative molecular-level framework linking salt concentration to electrochemical stability remain absent. Here, we develop an integrated theoretical–experimental framework that quantitatively connects solvation structure, thermodynamic activities, and electronic structure to electrochemical stability for LiPF 6 :EC:EMC (3:7 v:v). Molecular dynamics (MD) simulations, a lattice fluid theory, X-ray absorption spectroscopy (XAS), and density functional theory (DFT) are combined to predict electrolyte stability across concentration. We derive simple, analytic expressions for the activities of species, which are then experimentally parameterized using Raman spectroscopy and validated against MD simulations and experiment. Increasing salt concentration is found to enhance PF 6 − participation in the Li + coordination shell while suppressing free solvent populations, leading to systematic shifts in the activities of species and an expanded electrochemical stability window. The lattice fluid theory directly links solvation structure to measurable shifts in redox potentials via the Nernst equation, which we confirm experimentally. DFT calculations predict concentration-dependent shifts in unoccupied electronic states, which are validated by O and F K-edge X-ray absorption spectroscopy. These shifts provide the physical origin for the activity changes predicted by lattice fluid theory, while frontier orbital analysis further rationalizes the evolution of interphase composition arising from enhanced PF 6 − reactivity at high concentrations. This work establishes a predictive protocol connecting solvation structure, thermodynamic activity, and electronic structure with electrolyte stability, enabling rational design of electrolytes with tailored stability windows.

The pyrochlore vanadates are compelling candidates for next-generation dissipationless devices. and are ferromagnetic insulators (T 70 K) that are believed to exhibit the magnon Hall effect and are expected to host topological magnons. Their completely dissipationless magnon edge states could be harnessed to realize low-power information transport in spintronic or magnonic devices. As a crucial step in the realization of devices, we synthesize the first thin films of pyrochlore on isostructural substrates and explore the evolution of their magnetic properties down to the ultrathin limit. All films are insulating ferromagnets with transition temperatures of up to the bulk value (T 68 K) that decrease with thickness according to finite-size effects. Our films also exhibit a change in anisotropy from in-plane to out-of-plane easy axis coincident with the development of partial strain relaxation and nonzero magnetic hysteresis in an applied field. This evolution demonstrates the impact of strain on magnetic anisotropy and paves the way to tunable magnon topology.

Exchange bias fields at antiferromagnet/ferromagnet (AFM/FM) interfaces play a crucial role in the performance of spintronic devices. Despite extensive research, the physical origin of exchange bias remains incompletely understood. In this study, we conduct a detailed investigation of a prototype AFM/FM interface widely used in spintronic applications, i.e., the IrMn/CoFeB interface. High-resolution synchrotron X-ray measurements reveal the existence of uncompensated Mn spins at the interface. While most of these spins are strongly coupled to the adjacent CoFeB layer, a small fraction remains pinned to the underlying IrMn underlayer. Element-specific X-ray magnetic circular dichroism hysteresis loops show that these pinned spins can be switched by increasing the annealing magnetic field. Furthermore, micromagnetic simulations indicate that an imbalance in the quantity of antiparallel pinned spins contributes to the observed variation in exchange bias. Overall, these findings offer important insights into the microscopic mechanisms governing exchange bias and its tunability.

Large linear positive magnetoresistance (LPMR) in topological and magnetic materials remains a subject of intense debate, particularly in noncollinear spin systems where spin-dependent scattering complicates charge transport. Manganese phosphide (MnP), a helimagnetic binary pnictide with multiple field-induced magnetic transitions, provides a useful platform to investigate the interplay between complex magnetism and electronic topology. Here, we present a comprehensive experimental and theoretical investigation of phase-dependent magnetotransport in high-quality MnP single crystals. Hall measurements reveal an anomalous Hall effect dominated by skew scattering at high temperatures and a finite topological Hall effect in the noncollinear fan (FAN) and low-temperature screw (SCR) phases. At low temperatures, we observe a large, non-saturating LPMR reaching nearly 800 percent at 4 K and 15 T, with a pronounced linear field dependence in the field-polarized ferromagnetic (FM2) state. First-principles calculations reveal a strongly anisotropic semi-Dirac-like band at the Y point that progressively approaches the Fermi level from the SCR to FAN and FM2 states. Our analysis indicates that the resulting small Fermi pocket can access the extreme quantum-limit regime at experimentally accessible fields, providing a microscopic framework for the observed LPMR within Abrikosov's quantum magnetoresistance theory.

High entropy oxides (HEOs) can possess long-range ordered magnetic states despite their extreme chemical disorder. Very little is known about how the different chemical constituents in HEOs contribute to the emergence of these magnetic states. In this work, we leverage element-specific magnetometry attained via x-ray magnetic circular dichroism (XMCD) to understand how magnetic order is driven in two ferrimagnetic spinel-structured HEOs with compositions (Cr,Mn,Fe,Co,Ni)_3O_4 and (Cr,Mn,Fe,Co,Ni)_2.4Ga_0.6O_4. We find that while the magnetic transition is simultaneous for all chemical species, the rate at which their magnetic moments grow is strongly cation dependent. This behavior is explained by the varying 3d crystal field level fillings of the magnetic cations, which in turn determine their ability to participate in the different magnetic exchange pathways available in the spinel structure. Dominant A-B sublattice exchange enables some species to harden rapidly (e.g. tetrahedral Fe^3+ and octahedral Ni^2+) while others exhibit a sluggish transition due to frustration from competing interactions (e.g. octahedral Fe^3+ and Cr^3+). Non-magnetic substitution suppresses these differences, introducing broken magnetic linkages that relieve frustration. Tailoring the magnetism of HEO spinels therefore requires detailed knowledge of both their site selectivities and their exchange pathways.

Multiferroics that combine ferroelectricity and magnetic order are attractive for electronic and spintronic technologies, yet chemical disorder that promotes relaxor ferroelectricity usually suppresses long-range magnetic order. Here, we report entropy-stabilized relaxor multiferroicity in epitaxial hexagonal (Tb0.2Dy0.2Ho0.2Lu0.2Yb0.2)FeO3 thin films. Structural, magnetic, dielectric, and synchrotron spectroscopic measurements show the coexistence of relaxor ferroelectricity and long-range ferromagnetic order. We find that improper ferroelectricity remains robust against A-site configurational disorder, while the Fe sublattice preserves magnetic exchange. This separation of the microscopic origins of the polar and magnetic responses enables chemically disordered multiferroicity. Our results establish entropy engineering in hexagonal ferrites as a route toward multifunctional oxide thin films and provide a general design strategy for high-entropy multiferroics.

High-entropy perovskite oxides offer a promising platform for tailoring magnetic functionality through compositional complexity; however, it remains unclear how targeted substitution of 4d transition metals modifies oxygen-mediated electronic structure and element-specific magnetic interactions. To address this question, we investigate the effect of Mo and Ru substitution on the electronic structure and magnetism of high-entropy perovskite oxide thin films using O K-edge and transition-metal L-edge X-ray absorption spectroscopy, X-ray magnetic circular dichroism (XMCD), and X-ray linear dichroism. O K-edge spectra reveal that Ru enhances O 2p-metal d hybridization, whereas Mo modifies charge distribution and local exchange pathways within the transition-metal sublattice. Multiplet analysis shows that Mn and Ni retain stable Mn4+ and Ni2+ states, while Co acts as the primary charge-compensation reservoir through changes in the Co2+/Co3+ ratio. Temperature-dependent XMCD demonstrates that these substitutions selectively reshape the magnetic exchange network, redistributing spin polarization among the constituent elements. Quantitative XMCD sum-rule analysis reveals that Mo substitution produces the highest reconstructed total magnetic moment across the measured temperature range, reaching values at low temperature that are nearly an order of magnitude larger than those observed in the Ru-containing compositions. These results establish a composition-driven strategy for tuning covalency, charge redistribution, and the balance between localized and itinerant magnetism in high-entropy oxide thin films, providing a pathway toward the design of tunable spintronic and multifunctional oxide materials.

Heterostructures composed of heavy metal and van der Waals (vdW) magnets serve as platforms to investigate magnetotransport properties, enabling the electric readout of the spin-flop transition in the vdW antiferromagnet. We investigate the spin and orbital contributions to magnetism in Pt/exfoliated multilayer CrPS4 heterostructure using the synchrotron-radiation based x-ray magnetic circular dichroism technique measured in the total electron yield (TEY) mode. The TEY detection, with probing depth of 5-10 nm, mainly reflects the interfacial magnetic behavior near the Pt/CrPS4 boundary. A spin-flop transition appears near 0.7 T in both the CrPS4 single crystal and the Pt/CrPS4 heterostructures. The total Cr moment remains similar to 2 mu(B)/f.u. in both systems at 14 T and 6 K. In Pt/CrPS4, the orbital moment is strongly modulated by Pt, as manifested in the enhancement from similar to 0.1 mu(B)/f.u. in CrPS4 to similar to 0.5 mu(B)/f.u. in Pt/CrPS4, an effect attributable to the strong spin-orbit coupling with Pt. At 25 K, the total Cr moment reduces to similar to 1.1 mu(B)/f.u. in both systems. The Cr orbital moment in CrPS4 remains low similar to 0.1 mu(B)/f.u., whereas in Pt/CrPS4 it remains high similar to 0.5 mu(B)/f.u. These findings provide qualitative evidence of robust spin-orbit coupling and orbital hybridization at Pt/CrPS4 interface, and highlight the potential of heavy metal/vdW antiferromagnet heterostructures for spin-orbitronic device applications.

Chromium ditelluride, CrTe2, is an attractive candidate van der Waals material for hosting 2D magnetism. However, how the room-temperature ferromagnetism of the bulk evolves as the sample is thinned to the single-layer limit has proved controversial. This, in part, reflects its metastable nature, vs. a series of more stable self-intercalation compounds with higher relative Cr:Te stoichiometry. Here, exploiting a recently developed method for enhancing nucleation in molecular-beam epitaxy growth of transition-metal chalcogenides, we demonstrate the selective stabilisation of high-coverage CrTe2 and Cr2+εTe3 epitaxial monolayers. Combining X-ray magnetic circular dichroism, scanning tunnelling microscopy, and temperature-dependent angle-resolved photoemission, we demonstrate that both compounds order magnetically with a similar TC. We find, however, that monolayer CrTe2 forms as an antiferromagnetic metal, while monolayer Cr2+εTe3 hosts an intrinsic ferromagnetic semiconducting state. This work thus demonstrates that control over the self-intercalation of metastable Cr-based chalcogenides provides a powerful route for tuning both their metallicity and magnetic structure, establishing the CrxTey system as a flexible materials class for future 2D spintronics.

Electrolyte stability dictates the performance and lifetime of Li-ion batteries, yet a molecular level understanding of how salt concentration governs both thermodynamics and electronic structure remains incomplete. Here, we present an integrated study that links solvation environments, activity coefficients, and electronic structure across a wide range of LiPF6 concentrations in ethylene carbonate:ethyl methyl carbonate (EC:EMC, 3:7 v:v) electrolytes. From molecular dynamics simulations and Raman spectroscopy, we find increasing salt concentration reduces the number of species coordinating Li+ and suppresses free PF6- , EC, and EMC populations, which we connect to a lattice fluid theory that demonstrates systematic shifts in redox potentials from the changes in activity coefficients. In parallel, density functional theory calculations reveal how salt concentration reshapes the density of states, shifts frontier orbital energies, and thereby tunes electrode interfacial reactivity. X-ray absorption spectroscopy confirms these electronic structure variations. By combining thermodynamic and electronic structure perspectives, an approach not previously applied to electrolyte design, we show how concentrated electrolytes stabilize solvents and anions through Li+ association, shift the Li/Li+ redox couple to more positive potentials, and enhance PF−6- reactivity, promoting inorganic rich cathode electrolyte interphases. Importantly, this work establishes a direct link between solvation, electrochemical stability, and electronic structure, offering design principles for next-generation electrolytes with improved stability in high voltage Li-ion batteries.

Molecular cerium complexes are of interest due to their remarkable redox and photophysical properties. We have investigated the ligand tunability of the electronic structure and properties of cerium(IV) complexes with functionalized tetradentate N2O2-donor ligands: [CeIV(LtBu)2] (1), [CeIV(LH)2] (2) and [CeIV(LNO2)2] (3), where H2LtBu = bis(2-hydroxy-3,5-di-tert-butylbenzyl)(2-pyridylmethyl)amine, H2LH = bis(2-hydroxybenzyl)(2-pyridylmethyl)amine and H2LNO2 = bis(2-hydroxy-5-nitrobenzyl)(2-pyridylmethyl)amine. These compounds all exhibit a quasi-reversible one-electron reduction to cerium(III), with the redox potential correlating with the electron donor-acceptor characteristics of the ligand substituents. This correlation is rationalized by energy stabilization of the HOMO, as determined by density functional theory calculations, and is consistent with arene π → Ce 4f* ligand-to-metal charge transfer bands. The L3-edge XANES exhibits minimal variation in Ce 4f occupation for the three compounds, which suggests that the 4f covalent character and composition of the ground-state character do not vary significantly across the series. However, M4,5-edge XAS shows charge transfer satellites that subtly differ in shape and energy, indicating small distinctions in ligand-to-metal charge transfer for the compounds, consistent with small differences in temperature-independent magnetism. The ability to modulate the redox and optical properties of cerium complexes through ligand derivatization highlights the potential for customizable molecular cerium catalysts and photocatalysts.

Nickelate materials offer diverse functionalities for energy and computing applications. Lithium nickel oxide (LiNiO2) is an archetypal layered nickelate, but the electronic structure of this correlated material is not yet fully understood. Here we investigate the temperature-dependent speciation and spin dynamics of Ni ions in LiNiO2. Ab initio simulations predict that Ni ions disproportionate into three states, which dynamically interconvert and whose populations vary with temperature. These predictions are verified using x-ray absorption spectroscopy, x-ray magnetic circular dichroism, and resonant inelastic x-ray scattering at the Ni L3,2-edge. Charge-transfer multiplet calculations consistent with disproportionation reproduce all experimental features. Our results support a model of dynamic disproportionation that explains diverse physical observations of LiNiO2, including magnetometry, thermally activated electronic conduction, diffractometry, core-level spectroscopies, and the stability of ubiquitous antisite defects. This unified understanding of the material properties of LiNiO2 is important for applications of nickelate materials as battery cathodes, catalysts, and superconductors.

Chromium ditelluride, CrTe_2, is an attractive candidate van der Waals material for hosting 2D magnetism. However, how the room-temperature ferromagnetism of the bulk evolves as the sample is thinned to the single-layer limit has proved controversial. This, in part, reflects its metastable nature, vs. a series of more stable self-intercalation compounds with higher relative Cr:Te stoichiometry. Here, exploiting a recently-developed method for enhancing nucleation in molecular beam epitaxy growth of transition-metal chalcogenides, we demonstrate the selective stabilisation of high-coverage CrTe_2 and Cr_2+εTe_3 epitaxial monolayers. Combining X-ray magnetic circular dichroism, scanning tunnelling microscopy, and temperature-dependent angle-resolved photoemission, we demonstrate that both compounds order magnetically with a similar Tc. We find, however, that monolayer CrTe_2 forms as an anti-ferromagnetic metal, while monolayer Cr_2+εTe_3 hosts an intrinsic ferromagnetic semiconducting state. This work thus demonstrates that control over the self-intercalation of metastable Cr-based chalcogenides provides a powerful route for tuning both their metallicity and magnetic structure, establishing the Cr-Te system as a flexible materials class for future 2D spintronics.

The increased capacity offered by oxygen-redox active cathode materials for rechargeable lithium- and sodium-ion batteries (LIBs and NIBs, respectively) offers a pathway to the next generation of high-gravimetric-capacity cathodes for use in devices, transportation and on the grid. Many of these materials, however, are plagued with voltage fade, voltage hysteresis and O2 loss, the origins of which can be traced back to changes in their electronic and chemical structures on cycling. Developing a detailed understanding of these changes is critical to mitigating these cathodes' poor performance. In this work, we present an analysis of the redox mechanism of P2-Na0.67[Mg0.28Mn0.72]O2, a layered NIB cathode whose high capacity has previously been attributed to trapped O2 molecules. We examine a variety of charge compensation scenarios, calculate their corresponding densities of states and spectroscopic properties, and systematically compare the results to experimental data: 25Mg and 17O nuclear magnetic resonance (NMR) spectroscopy, operando X-band and ex situ high-frequency electron paramagnetic resonance (EPR), ex situ magnetometry, and O and Mn K-edge X-ray Absorption Spectroscopy (XAS) and X-ray Absorption Near Edge Spectroscopy (XANES). Via a process of elimination, we suggest that the mechanism for O redox in this material is dominated by a process that involves the formation of strongly antiferromagnetic, delocalized Mn-O states which form after Mg2+ migration at high voltages. Our results primarily rely on noninvasive techniques that are vital to understanding the electronic structure of metastable cycled cathode samples.

Calculations and measurements of polarization-dependent soft X-ray scattering intensity are presented during a magnetic hysteresis cycle. It is confirmed that the dependence of the intensity on the magnetic moment can be linear, quadratic or a combination of both, depending on the polarization of the incident X-ray beam and the direction of the magnetic moment. With a linearly polarized beam, the scattered intensity will have a purely quadratic dependence on the magnetic moment when the magnetic moment is parallel to the scattering plane. However, with the magnetic moment perpendicular to the scattering plane, there is also a linear component. This means that, when measuring the hysteresis with linear polarization during a hysteresis cycle, the intensity will be an even function of the applied field when the change in the magnetic moment (and field) is confined within the scattering plane but becomes more complicated when the magnetic moment is out of the scattering plane. Furthermore, with circular polarization, the dependence of the scattered intensity on the moment is a combination of linear and quadratic. With the moment parallel to the scattering plane, the linear component changes with the helicity of the incident beam. Surprisingly, in stark contrast to absorption studies, even when the magnetic moment is perpendicular to the scattering plane there is still a dependence on the moment with a linear component. This linear component is completely independent of the helicity of the beam, meaning that the hysteresis loops will not be inverted with helicity.