α-MnTe is a prototypical altermagnet exhibiting a strong anomalous Hall effect (AHE), despite having a nearly vanishing magnetization. Lately, sample-to-sample variations of the amplitude of the AHE have raised concerns of a possible defect related origin, especially in thin films. Here, we study the AHE in α-MnTe films grown on SrF2 that have the crystal structure and m'm'm magnetic point group symmetry expected for bulk. By studying the scaling of the AHE with conductivity for those films and previously reported measurements in the literature, we find that sample-to-sample variations are well explained by a scaling law consistent with a hopping origin. Importantly, a comparison with other magnetic semiconductors reveals the colossal amplitude of the AHE of α-MnTe compared to its measured spontaneous magnetization from magnetometry and polarized neutron reflectivity. Our findings address the important fundamental question of the origin of the AHE of α-MnTe and further demonstrate the potential of altermagnets as promising spintronic materials.

A long spin‐lifetime of electrons is the holy grail of spintronics, a field exploiting the electron angular momentum as an information carrier and storage unit. Previous reports indicated a spin lifetime, τ s near 10 ns at best in graphene‐based devices at low temperatures. The observation of τ s approaching the ultralong 1,000 ns at room temperature in natural graphite crystals is detailed using magnetic resonance spectroscopy. The relaxation time shows a giant anisotropy: the lifetime of spins, polarized perpendicular to the graphite plane, is more than 50 times longer than for the in‐plane polarization. The temperature dependence of τ s proves that diffusion of spins to the crystallite edges, where relaxation occurs, limits the lifetime. This suggests that graphite is an excellent candidate for spintronic applications, seamlessly integrating with emerging 2D van der Waals technologies.

Time-resolved photoconductivity is widely used to characterize non-equilibrium charge-carrier lifetime, impurity content, and solar cell efficiency in a broad range of semiconductors. Most measurements are limited to the detection of reflection of electromagnetic radiation at a single frequency and a single photoexciting light wavelength. We present a time-resolved photoconductivity instrument that enables broadband frequency detection (essentially from DC to 100 GHz), temperature-dependent measurements, and multiple excitation photon energy. The measurement is realized with the help of a coplanar waveguide, which acts as an efficient antenna and whose performance was tested over 10 MHz-10 GHz. The instrument enables the study of surface and bulk charge-recombination specific processes.

Plastic waste, one of the most critical problems for humankind, poses severe threats to ecosystems, wildlife, and human health. Tracing, quantifying, and identifying types of plastic waste are crucial to understanding its environmental pathways and developing targeted strategies for reduction, recycling, and remediation. To contribute to addressing this global issue, we investigated the spin-labeling capabilities of chlorine dioxide (ClO2) radicals introduced into poly(ethylene terephthalate) and utilized electron spin resonance spectroscopy for detection. The technique is capable of identifying plastic species, as the unpaired electron of the radical molecule is strongly sensitive to its local environment through its coupling parameters. Temperature-dependent measurements revealed that the molecules are immobilized at low temperatures and exhibit well-resolved anisotropic and hyperfine spectra that are quantitatively described by a model spin Hamiltonian. Even above the melting point of water, certain degrees of freedom remain restricted as a result of the polymer matrix. Furthermore, employing a time-series measurement at room temperature enabled us to determine the diffusion coefficient of the molecule in the polymer

The kagome lattice, with its inherent geometric frustration, provides a rich platform for exploring intriguing magnetic phenomena and topological electronic structures. In reduced-symmetry structures, such as twisted kagome systems involving rare earth elements, additional anisotropy can arise, enabling intriguing properties including spin-ice states, magnetocaloric effects, noncollinear magnetic ordering, and the anomalous Hall effect. Here, we report the synthesis of single crystals of ErPdPb, which features a twisted kagome lattice net of Er atoms within the hexagonal ZrNiAl-type structure, and we investigate its magnetic, electronic, and thermal properties. The material exhibits a highly anisotropic, correlated magnetic state below 2.7 K, as evidenced by magnetic, transport, and heat capacity measurements. Density functional theory (DFT) calculations indicate strong easyaxis anisotropy, consistent with experiment and crystal-field expectations, as well as quasi-one-dimensional bands and a spin-split saddle point at the zone center. The coexistence of competing magnetic interactions along different crystallographic directions suggests an inherent degree of frustration. ErPdPb thus provides a promising platform for exploring the interplay of frustration, anisotropy, and electronic structure in a twisted kagome lattice.

We investigate the electronic structure and Fermi surface of Co_1/3TaS_2 using angle-resolved photoemission spectroscopy (ARPES) combined with theoretical modeling beyond standard density functional theory (DFT+U). A shallow electron pocket, the so-called β feature, is observed at the Fermi level near the corner of the superlattice Brillouin zone, representing the first experimental observation of this feature in an intercalated TaS_2 compound. Similar pockets have been reported in X_1/3NbS_2 (X = Co, Cr, Ni), where their surface versus bulk origin remains actively debated. Because conventional DFT+U does not capture this feature, we employ cluster perturbation theory (CPT) to incorporate an explicit treatment of strong electron correlations (U) on the Co sites. CPT successfully reproduces the β feature, demonstrating its origin from correlation-driven bulk states rather than surface effects. To further substantiate this conclusion, we studied a reduced Co-content sample, Co_0.22TaS_2, where the reduced charge transfer modifies the Co-derived states near the Fermi level. Its electronic structure remains largely similar to that of pristine 2H-TaS_2, showing only a minor overall energy shift and lacking the β feature, consistent with disrupted long-range Co ordering and modified orbital character near the Fermi level. We demonstrate that the β feature arises from strong local correlations on the Co sites and requires long-range crystallographic order among intercalated Co atoms to maintain coherence. These results highlight the importance of strong electronic correlations in magnetically intercalated transition-metal dichalcogenides and provide a microscopic understanding of features not captured by conventional DFT+U.

Polytypism in transition metal dichalcogenides (TMDs) introduces an additional degree of freedom for tailoring the electronic properties of layered van der Waals materials. Polytypes with larger unit cells, spanning four or six layers, can be viewed as natural homostructures, since their atomic composition remains identical across the layers. The resultant crystalline environments can potentially give rise to exotic electronic states, earning these materials recent attention. In this study, we examine structural and charge transport properties of metallic and superconducting 4Ha-NbSe2. We find that the compound has a highly disordered stacking of layers, which impedes interlayer coherence, as demonstrated by detailed out-of-plane resistivity measurements, and effectively tunes the bulk system towards an atomically thin limit. The disordered structure largely accounts for the enhanced resistivity anisotropy and superconducting upper critical field, when compared to 2Ha-NbSe2. This phenomenon can be exploited to promote quasi-two-dimensional physics in bulk crystals, and our study also underscores the importance of thorough structural characterization when investigating large-unit-cell polytypes of TMDs.

Murunskite (K2FeCu3S4) is a layered sulfosalt chalcogenide that occupies a unique position between the cuprate and iron pnictide families: it shares electronic characteristics with the former and adopts the crystal structure of the latter. Despite a completely random distribution of magnetic Fe within a nonmagnetic Cu matrix, murunskite exhibits a well-defined quarter-zone antiferromagnetic transition at 97 K and complete orbital order below 30 K. These findings reveal the unexpected emergence of long-range order in a high-entropy-like environment. This inherent robustness to site disorder in a layered structure makes murunskite a paradigmatic system for further studies. Here, we investigate doping strategies in murunskite to assess how its electronic and magnetic properties can be tuned. Using melt-growth techniques, we achieve substitutions at the magnetic metal site (Fe), spacer cation (K), and sulfur ligand (S), which significantly influence transport and magnetic properties. In addition, we use ionic-liquid gating on the parent compound and observe a gate-dependent suppression of resistivity, confirming the potential for electrostatic control over transport. Our results demonstrate the chemical and electronic plasticity of murunskite, offering a valuable platform for co-engineering disorder, magnetism, and transport, and opening avenues to explore quantum phenomena in correlated and high-entropy materials.

The development of multifunctional solid-state materials is key to advancing lithium-ion batteries with enhanced safety and simplified architectures. Here, we report a scalable, highly efficient (near 100%), solvent-free mechanochemical synthesis of hexagonal boron nitride (hBN) functionalized with lithium oxalate (Li_2C_2O_4), yielding a novel lamellar composite that functions both as a lithium-ion conductor and separator. The high-energy milling process promotes exfoliation of hBN and covalent attachment of oxalate groups at edge and defect sites, forming a brown, nanocrystalline material with uniform lithium distribution. The composite exhibits room-temperature ionic and negligible electronic conductivity, thermal stability at least up to 350 ^∘C, and hosts stable free radicals enabling its use as a spin label. The synthesis produces no byproducts and can be extended towards lithium doping via secondary mechanochemical steps, creating highly doped, chemically stable phases that host additional Li for ionic conduction. These results introduce a new class of lithium-rich, boron nitride-based solids for solid-state batteries, combining ion conduction, mechanical robustness, and thermal resilience in a single material platform.

Murunskite (K 2 FeCu 3 S 4 ) bridges the two known families of high‐temperature superconductors, cuprates and iron‐pnictides, structurally and electronically. Like these families, murunskite exhibits an antiferromagnetic (AF)‐like response with an ordered phase below 97 K. The magnetic iron atoms are randomly distributed over one‐quarter of the sites in two‐dimensional planes, while the remaining sites are occupied by non‐magnetic copper, evoking the notion of a high‐entropy magnetic alloy. This intriguing magnetic transition is studied by neutron, Mössbauer, and X‐ray photoelectron spectroscopy (XPS) measurements on single crystals. The AF order has a nearly commensurate quarterzone wave vector. In the paramagnetic state, Mössbauer spectroscopy identifies two iron sites, associated with Fe 3 + or Fe 2 + oxidation states as observed by XPS, which merge into a third site upon cooling, indicating an orbital transition. This cascade of local transitions transforms iron atoms from a fully orbitally and magnetically disordered state to a homogeneously ordered state in inverse space, while still being randomly distributed in real space. This finding challenges the traditional paradigm of magnetism in insulators, which relies on a direct connection between crystal structure and the location of magnetic moments.

Ferrofluids, composed of magnetic nanoparticles suspended in a non-magnetic carrier liquid, have attracted considerable attention since their discovery in the 1960s. Their combination of liquid and magnetic properties gives rise to complex behaviors and unique functionalities, enabling a wide range of technological applications. Among these is the ability of the magnetic material to be moved by and to absorb heat when exposed to an external magnetic field – a process that can occur through various dissipation mechanisms depending on the system. A detailed understanding of these mechanisms is crucial for tailoring materials to specific applications. We provide a comprehensive overview of the theoretical principles underlying different energy dissipation processes and propose a coherent framework for their interpretation. Particular attention is devoted to describing the frequency-dependent susceptibility, which is the key parameter to describe dissipation. We demonstrate that dissipation, predicted from magnetometry-based studies, matches well with direct, frequency-dependent calorimetric results, expanding the available frequency range of the characterization. The demonstrating measurements were carried out with a dilute ferrofluid containing magnetite nanoparticles of a mean diameter of 10.6 nm.

Kagome magnets represent a promising class of materials that exhibit intriguing electronic and magnetic properties, and they have recently garnered significant attention. While most kagome-lattice compounds are hexagonal, here we report the single-crystal growth and physical property measurements of similar compounds RFe_6Ge_6 (R = Y, Dy, Tb), which crystallize in an orthorhombic structure. The structure can be derived from a hexagonal prototype RFe_3Ge_2 by replacing every other R atom with a covalent Ge_2 dimer. Ordering of the latter makes the structure orthorhombic the kagome net slightly distorted, and the three Fe sites formally inequivalent. The iron and rare-earth sublattices order independently: the Fe moments order above 400 K having, with ferromagnetic Kagome planes stacked antiferromagnetically, while the rare-earth moments order below 9 K. While TbFe_6Ge_6 exhibits a single magnetic ordering transition associated with the Tb atoms, DyFe_6Ge_6 shows two distinct magnetic phase transitions, which are strongly influenced by crystal electric field effects on the Dy^3+ ions. Density functional theory (DFT) calculations show that the ferromagnetic ordering of the Fe planes is driven by a high density of states at the Fermi energy. They also reveals three dramatically different structural energy scales: R and Ge_2 form alternating 1D chains perpendicular to the kagome planes, and violating this alternation incurs a huge energy cost. Aligning these chains is less costly, and actual 2D order of anti-aligned chains costs very little. These compounds represent a unique class of materials, offering new possibilities to investigate the interplay between the distinct crystal lattice geometry and the underlying electronic and magnetic properties.

Altermagnets (AMs) are a new class of magnetic materials that combine the beneficial spintronics properties of ferromagnets and antiferromagnets, garnering significant attention recently. Here, we have identified altermagnetism in a layered intercalated transition metal diselenide, CoNb_4Se_8, which crystallizes with an ordered sublattice of intercalated Co atoms between NbSe_2 layers. Single crystals are synthesized, and the structural characterizations are performed using single crystal diffraction and scanning tunneling microscopy. Magnetic measurements reveal easy-axis antiferromagnetism below 168 K. Density functional theory (DFT) calculations indicate that A-type antiferromagnetic ordering with easy-axis spin direction is the ground state, which is verified through single crystal neutron diffraction experiments. Electronic band structure calculations in this magnetic state display spin-split bands, confirming altermagnetism in this compound. The layered structure of CoNb_4Se_8 presents a promising platform for testing various predicted properties associated with altermagnetism.

The kagome lattice, known for its strong frustration in two dimensions, hosts a variety of exotic magnetic and electronic states. A variation of this geometry, where the triangular motifs are twisted to further reduce symmetry, has recently revealed even more complex physics. HoAgGe exemplifies such a structure, with magnetic and electronic properties believed to be driven by strong in-plane anisotropy of the Ho spins, effectively acting as a two-dimensional spin ice. In this study, using a combination of magnetization, Hall conductivity measurements, and density functional theory calculations, we demonstrate how various spin-ice states, stabilized by external magnetic fields, influence the Fermi surface topology. More interestingly, we observe sharp transitions in Hall conductivity without concurrent changes in magnetization when an external magnetic field is applied along a particular crystallographic direction, underscoring the role of strong magnetic frustration and providing a new platform for exploring the interplay between magnetic frustration, electronic topology, and crystalline symmetry. These results also highlight the limitations of a simple spin-ice model, suggesting that a more sophisticated framework is necessary to capture the subtle experimental nuances observed.

Ti$_3$C$_2$T$_x$ is a leading compound within the MXenes family and can find host in widespread applications. It is synthesized by selectively etching layers from the Ti$_3$AlC$_2$ precursor, and this process typically introduces surface terminations, T$_x$, such as $-$OH, $=$O, or $-$F. However, the aggressive chemical conditions required for its preparation, as well as exposure to air, humidity, and heat, can lead to impurity phases that potentially compromise its desirable properties. We reveal a two-step oxidation process during heat treatment, where initial oxidation occurs between layers without altering the integrity of the Ti$_3$C$_2$ layered structure, followed by the formation of anatase TiO$_2$ at elevated temperatures. The process was carefully monitored using \emph{in situ} Raman spectroscopy and \emph{in situ} microwave conductivity measurements, employed to Ti$_3$C$_2$T$_x$ prepared using various etching techniques involving concentrated HF, LiF + HCl, and HF + HCl mixtures. The oxidation process is heavily influenced by the synthesis route and surface chemistry of Ti$_3$C$_2$T$_x$, with fluoride and oxyfluoride groups playing a pivotal role in stabilizing the anatase phase. The absence of these groups, in contrast, can lead to the formation of rutile TiO$_2$.

Ti3C2Tx is a leading compound within the MXenes family and can find host in widespread applications. It is synthesized by selectively etching layers from the Ti3AlC2 precursor, and this process typically introduces surface terminations, Tx, such as OH, O, or F. However, the aggressive chemical conditions required for its preparation, as well as exposure to air, humidity, and heat, can lead to impurity phases that potentially compromise its desirable properties. Herein, a two‐step oxidation process is revealed during heat treatment, where initial oxidation occurs between layers without altering the integrity of the Ti3C2‐layered structure, followed by the formation of anatase TiO2 at elevated temperatures. The process is carefully monitored using in situ Raman spectroscopy and in situ microwave conductivity measurements, applied to Ti3C2Tx prepared using various etching techniques involving concentrated hydrofluoric acid, LiF + HCl, and HF + HCl mixtures. The oxidation process is heavily influenced by the synthesis route and surface chemistry of Ti3C2Tx, with fluoride and oxyfluoride groups playing a pivotal role in stabilizing the anatase phase. The absence of these groups, in contrast, can lead to the formation of rutile TiO2.

Optical trapping microscopy unravels open questions in statistical physics by making ultraprecise measurements of Brownian motion in diverse fluid environments. Moreover, the advent of pulsed lasers promises to push the boundaries even further, offering insights on how the compressibility of fluid flow affects Brownian particles at previously unexplored time scales.

The measurement and description of the charge-carrier lifetime (τc) is crucial for the wide-ranging applications of lead-halide perovskites. We present time-resolved microwave-detected photoconductivity decay (TRMCD) measurements and a detailed analysis of the possible recombination mechanisms including trap-assisted, radiative, and Auger recombination. We prove that performing injection-dependent measurement is crucial in identifying the recombination mechanism. We present temperature and injection level dependent measurements in CsPbBr3, which is the most common inorganic lead-halide perovskite. In this material, we observe the dominance of charge-carrier trapping, which results in ultra-long charge-carrier lifetimes. Although charge trapping can limit the effectiveness of materials in photovoltaic applications, it also offers significant advantages for various alternative uses, including delayed and persistent photodetection, charge-trap memory, afterglow light-emitting diodes, quantum information storage, and photocatalytic activity.

The discovery of an anomalous Hall effect (AHE) sensitive to the magnetic state of antiferromagnets can trigger a new era of spintronics, if materials that host a tunable and strong AHE are identified. Altermagnets are a new class of materials that can under certain conditions manifest a strong AHE, without having a net magnetization. But the ability to control their AHE is still lacking. In this study, we demonstrate that the AHE in altermagnetic α-MnTe grown on GaAs(111) substrates can be "written on-demand" by cooling the material under an in-plane magnetic field. The magnetic field controls the strength and the coercivity of the AHE. Remarkably, this control is unique to α-MnTe grown on GaAs and is absent in α-MnTe grown on SrF2. The tunability that we reveal challenges our current understanding of the symmetry-allowed AHE in this material and opens new possibilities for the design of altermagnetic spintronic devices.

Skyrmion lattices (SkL) in centrosymmetric materials typically have a magnetic period on the nanometer-scale, so that the coupling between magnetic superstructures and the underlying crystal lattice cannot be neglected. We reveal the commensurate locking of a SkL to the atomic lattice in Gd3Ru4Al12 via high-resolution resonant elastic x-ray scattering (REXS). Weak easy-plane magnetic anisotropy, demonstrated here by a combination of ferromagnetic resonance and REXS, penalizes placing a skyrmion core on a site of the atomic lattice. Under these conditions, a commensurate SkL, locked to the crystal lattice, is stable at finite temperatures – but gives way to a competing incommensurate ground state upon cooling. We discuss the role of Umklapp-terms in the Hamiltonian for the formation of this lattice-locked state, its magnetic space group, and the role of slight discommensurations, or (line) defects in the magnetic texture. We also contrast our findings with the case of SkLs in noncentrosymmetric material platforms.