The ability to control and manipulate time-reversal (T) symmetry-breaking phases with near-zero net magnetization is a sought-after goal in spintronic devices. The recently discovered hexagonal altermagnet manganese telluride (α-MnTe) is a prime example. It has a compensated altermagnetic ground state where the magnetic moments are aligned in each layer and stacked antiparallel along the c axis, yet it exhibits a spontaneous anomalous Hall effect (AHE) that breaks the T-symmetry with a vanishingly small c-axis ferromagnetic (FM) moment. However, the presence of three 120^∘ separated in-plane magnetic domains presents a challenge in understanding the origin of the AHE and the effective control of the altermagnetic state. Here we use neutron scattering to show that symmetry breaking anisotropic strain, induced by compressive uniaxial pressure along the nearest-neighbor (NN) Mn-Mn bond directions, detwins α-MnTe into a single in-plane magnetic domain. This control over in-plane domains allows us to unambiguously establish that the in-plane moments are aligned along the NNN Mn-Mn bond direction, irrespective of the applied strain directions. Mounting the sample on a piezoelectric strain cell along both NN and NNN directions can drive the sample into a single-domain state that significantly sharpens the AHE hysteresis loop and extends the AHE to lower temperatures. Furthermore, tuning the uniaxial strain reverses the sign of the AHE near room temperature. Remarkably, this is achieved without altering the altermagnetic phase-transition temperature or substantially changing the small c-axis FM moment. Combined with our phenomenological model, we argue that these effects result from the modification of the electronic Berry curvature by a combination of both spin-orbit coupling and strain. (See the full abstract in the PDF.)

Consolidation of diamond particles into high-strength bulk materials and composites is extremely challenging as it requires high sintering temperatures, at which diamond transforms into graphite, making it impossible to retain the sintered diamond phase. Here we report a synthetic approach based on spark plasma sintering that allows the stabilization of micron-scale diamond grains in composites, using cubic boron nitride (cBN) as the matrix and cobalt (Co) particles as a stabilizer, resulting in a hard-to-machine, tough material. We performed hypersonic speed impact tests on the composites using metal projectiles of different sizes. The composite withstands impact from ∅1 mm metal projectiles (speed Mach 7.5) but breaks apart during the impact from a larger ∅4 mm metal projectile (speed Mach 8.45). Interestingly, during this microsecond-scale impact and fracture event, embedded diamond particles in the composite undergo near-complete phase transformation to graphite. In-depth micro-structural characterizations of the fractured composite, supported by the molecular dynamics simulations reveal details on the impact-induced phase transformation and the creation of diamond-graphite interfaces, suggesting that the energy absorption is primarily enabled via phase change of diamond. Our findings provide a pathway to stabilize the diamond phase and a new understanding of phase transformation of diamond under extreme conditions.

Room-temperature superconductivity is arguably the greatest challenge in condensed matter physics, with significant practical and commercial implications if it can be solved. There are no physical laws preventing this from occurring; indeed, superconductivity has been observed in so many different materials under so many different conditions that it is almost a "generic" property of nonmagnetic metals. This guides our viewpoint that high-temperature superconductivity is possible, if difficult to realize. Here, we lay out two grand challenges facing the field, titled the Prediction Challenge and the Engineering Challenge, and put forward a programmatic approach for overcoming them. The Prediction Challenge addresses the fact that our ability to predict new conventional superconductors has dramatically advanced in recent years, but most predicted materials are not experimentally synthesizable. To address this challenge, we propose a shift from modeling the superconducting critical temperature and dynamic stability toward high-throughput ab initio and predictive thermodynamics/synthesis modeling. The Engineering Challenge describes how we can control superconductivity with various "knobs," including pressure, nanostructuring, and light. However, our ability to predict how a specific knob will modify a given superconductor is limited, making it difficult to fully exploit them. We describe the current status and identify areas where additional work is needed to fully exploit six of the most common knobs. Progress in both of these grand challenges, while closely integrating theory and experiment into a continuous feedback loop and incorporating insights from fields beyond physics and materials science, could unlock the underlying keys to room-temperature superconductivity.

The accelerated emergence of new materials is driving the search for high temperature superconductors, but rapid experimental validation remains a critical bottleneck, particularly for microscopic samples under high pressure. Here, we demonstrate one-step direct superconductivity validation through room-temperature, contact-free detection of remnant supercurrents. The technique utilizes a cryogen-free optically pumped atomic magnetometer to detect the temperature-dependent magnetic field produced by supercurrents of a superconductor. The superconducting transition is directly identified by the abrupt disappearance of magnetic field from the remnant supercurrent above the transition temperature and the reversal of the supercurrent direction upon reversing the applied magnetic field. Validated on YBCO microcrystals and REBCO tape, this technique detects pico-Tesla magnetic fields from supercurrents induced by the ambient Earth's magnetic field in a millimeter-sized REBCO square disk, as well as from sub-100 micrometer YBCO microcrystals compatible with high-pressure diamond anvil cells. The use of a ferrite flux guide enables sensitive detection from centimeter-scale distances. Requiring no electrical contacts, magnetic coils, or integrated magnetic sensors, this non-invasive, room-temperature platform offers a scalable approach for high-throughput screening and validation of superconductivity.

Mg_2IrH_6 is a metastable complex metal hydride with a predicted superconducting transition temperature as high as 170 K at ambient pressure. Following the synthesis of isomorphic, insulating Mg_2IrH_5 at low pressure, higher-pressure studies were conducted to investigate the phase behavior and compound formation in this system. X-ray diffraction and Raman spectroscopic measurements indicate that cubic Mg_2IrH_7 is stabilized above ca. 40 GPa and coexists with a related hexagonal hydride with likely composition near Mg_2IrH_5. Electrical transport measurements show that the cubic Mg_2IrH_7 is insulating, in agreement with ab initio predictions, and persists during room-temperature decompression until ∼20 GPa before reverting back to the cubic Mg_2IrH_5. The experimental results confirm ground-state structure predictions in the Mg-Ir-H system, and the formation of two nearly identical phases with surrounding compositions opens new opportunities to access superconducting Mg_2IrH_6 through non-equilibrium processing pathways.

AgSbTe2 is a well-known thermoelectric material with a high Seebeck coefficient and intrinsically low thermal conductivity, but its behavior under pressure remains largely unexplored. Here we report a systematic investigation of the structural, electronic, and transport properties of non-stoichiometric AgSbTe2 under high pressure. At ambient pressure, the material can be described as having a cubic crystal structure that remains stable up to 21.7 GPa beyond which it loses long-range structural order, while its crystal system fully recovers upon decompression. Remarkably, superconductivity emerges at a very low pressure of 0.38 GPa with an onset superconducting critical temperature (Tc) of 3.2 K. Tc increases with increasing pressure, reaching 6.9 K at 31.9 GPa, and peaks at 7.4 K during decompression. Magnetic-field-dependent transport measurements and electronic structure calculations reveal an evolution of the superconducting state driven by an enhanced electronic density of states at the Fermi level under compression. Our findings uncover pressure-induced superconductivity in AgSbTe2 and demonstrate that pressure can effectively tune the electronic ground state of thermoelectric materials, extending their functionality beyond thermoelectric energy conversion.

Intercalated van der Waals (vdW) magnets have attracted growing interest owing to their rich and highly tunable magnetic properties and their promise for ultracompact spintronic applications. A remarkable example is self-intercalated chromium tellurides (Cr1+δTe2), in which spatially ordered chromium atoms occupy the vdW gaps, yielding a variety of known compounds (e.g., Cr1.25Te2, Cr1.33Te2, and Cr1.5Te2) that host distinct and intriguing magnetic states. In this work, we uncover the existence of hidden, ordered self-intercalated phases that form spontaneously along with a twisted Cr1.5Te2 phase in chromium telluride nanoflakes grown by chemical vapor deposition. Using wide-field and scanning diamond nitrogen-vacancy center (NV) magnetometry, we unveil intricate magnetic structures in the chromium telluride flakes at the nanoscale and above room temperature. In a small nanoflake, the magnetization prefers an in-plane orientation in its interior with strong anisotropy but is tilted out of plane at the edges. In a large nanoflake, we observe complex magnetic profiles indicating the possible formation of nontrivial localized topological structures. Our work demonstrates the versatility of self-intercalation beyond known phases and the rich magnetic properties in a model vdW magnet, highlighting its great potential for room-temperature spintronic applications.

Orthorhombic air-stable two-dimensional (2D) antiferromagnet (AFM) CrSBr has attracted much research interest lately thanks to its rich magnetic behaviors together with its remarkable electronic, excitonic, and polaritonic properties. Here, we report a reliable electrochemical intercalation method by inserting large tetrabutylammonium (TBA+) ions into CrSBr layers. Magnetically, such intercalation efficiently suppresses the interlayer AFM and induces a ferromagnetic (FM) order with a much-enhanced transition temperature up to 200 K, nearly 70 K higher than the AFM onset of 132 K in pristine CrSBr. Electronically, the TBA+ intercalation not only increases the electric conductivity of CrSBr, which is further enhanced by magnetic fields, but also introduces a giant negative irreversible magnetoresistance. This work demonstrates the tunable magnetic and electronic properties of CrSBr as well as their interplay, paving the way for advanced spintronic and magnetic memory devices.

Superconductivity has been a vigorously researched topic since its discovery in 1911. Raising the superconducting transition temperature (Tc) has been the main driving force behind such long-sustained efforts due to its potential for impacting humanity and the fundamental knowledge gained from understanding this macroscopic coherent quantum state at high temperatures. The successful development of high-Tc superconductivity will make possible extraordinarily efficient generation, delivery, and utilization of energy and could also enable the development of controlled fusion while impacting other burgeoning fields like quantum computation and quantum electronics. However, progress has been hindered by a longstanding plateau in the record ambient-pressure Tc, unchanged since 1993. Subsequent significant advancements in Tc have been achieved only under high pressures, preventing the realization of superconductivity's full potential. To directly address this challenge, we developed a pressure-quench protocol (PQP) to stabilize pressure-induced/-enhanced superconducting states at ambient pressure. Here, we achieve a record ambient-pressure Tc of 151 K in the cuprate HgBa2Ca2Cu3O8+δ via PQP. The experimental results are further supported by synchrotron X-ray diffraction measurements and phonon and electronic structure calculations. This breakthrough opens avenues for stabilizing and exploring ambient-pressure high-Tc superconducting states and other quantum states that have been previously only accessible under pressure, paving the way for deeper understanding and practical applications of high-Tc superconductivity and beyond.

Topological spin textures in local moment systems hold great promise for technological applications due to their large magnetic moments, strong spin-orbit coupling (SOC), and high tunability. Finding new spin textures that are stable near room temperature is paramount to maximizing their potential for applications. Here, we provide a strategy for realizing topological spin textures at high temperatures by identifying rare earth (R) magnets ordering at or near room temperature. We demonstrate the feasibility of this strategy in one of these magnets, hexagonal Gd_5Pb_3, which orders at T_C = 285 K. The indication for topological spin textures comes from topological Hall effect (THE), which, in Gd_5Pb_3, occurs between T = 100 - 200 K, an order of magnitude higher temperature than in other reported R-based systems. Our results present an opportunity to explore the role of SOC, anisotropic exchange, geometric frustration, and magnetic interactions in stabilizing topological spin textures, and provide a pathway toward realizing them near room temperature in R-based magnets.

Structure-property relations of the recently discovered germanium allotrope oP32-Ge are examined using a variety of experimental high-pressure techniques and compared with the results of density functional theory (DFT) calculations. High-pressure single-crystal x-ray diffraction shows that the unit-cell parameters and atomic positions of oP32-Ge change continuously up to 6 GPa, while peak shape and diffuse-scattering features remain essentially unchanged. X-ray diffraction reveals a sluggish transformation of oP32-Ge to the beta-Sn Ge-II polymorph, i.e., the transition begins around 8 GPa and is complete by 12 GPa. The reconstructive transition is associated with the breakdown of oP32-Ge crystals into polycrystalline aggregates, which were examined up to 32 GPa. Synchrotron infrared absorption measurements indicate an increase in the band gap of oP32-Ge prior to the transition at 8 GPa to the higher-pressure metallic phase, which is characterized by high optical reflectivity. The DFT calculations of the structural and electronic properties are in good agreement with the measurements. Our experimental work conclusively shows that, under room-temperature quasihydrostatic compression, oP32-Ge remains in its semiconducting phase up to approximately 8 GPa, transforming into the Ge-II structure only by 12 GPa, a stability interval comparable to that of diamond-structured Ge (Ge-I). Crucially, we observe no anomalous structural or bonding changes over the range of conditions explored, indicating that the previously reported low-pressure superconductivity (near 2 GPa) must stem from subtle structural or stress-induced modifications accessible under the nonhydrostatic, low-temperature conditions of those experiments.

Correction for 'Cooperative enhancement of redox catalysis in divanadium complexes binucleated by 1,8-naphthyridine-2,7-dicarboxylate' by Simran Simran et al., Dalton Trans., 2025, 54, 15400-15405, https://doi.org/10.1039/D5DT01296A.

Scientific knowledge is increasingly dispersed across vast and heterogeneous scientific literature, where important claims are often implicit, evolving, and internally debated. While large language models (LLMs) have shown impressive performance in information extraction and summarization, their ability to recover latent scientific consensus remains unclear. Here, we investigate this problem in the context of high-temperature superconductivity (HTS), a long-standing and highly debated topic in condensed matter physics, as a challenging testbed. Using near 18,000 highly-cited publications over the past seven decades, we construct a structured knowledge graph linking competing superconducting mechanisms, material families, evidential modalities, and citation relations. We find that LLM-extracted representations recover coherent and physically interpretable structures, including family-dependent mechanism profiles, evidence-specific correlations, and citation-mediated temporal evolution of scientific beliefs. Ablation studies on LLM further show that the global structure remains robust across prompting, decoding, and model variations. Our results suggest that LLMs can indeed serve as scalable tools for deciphering scientific knowledge in domains characterized by competing interpretations and evolving knowledge.

In this study, chemically complex TiZrVCrNiFe-X alloys with X = Mn and MnCo were examined to determine how B-sublattice chemistry influences the stability of the C14 Laves phase during heating and the resulting magnetic response. Room-temperature X-ray diffraction and backscattered scanning electron microscopy show a dominant C14 (MgZn2, P63//mmc) matrix in both alloys, together with a minor V- and Cr-rich segregation at the few-percent level, consistent with solidification-related microsegregation. Co addition produces a measurable contraction of the C14 lattice, strongest along the c axis. Differential scanning calorimetry shows a shallow endothermic feature near 773-797 degrees C, indicating the onset of diffusion-assisted chemical rearrangement. In-situ high-temperature X-ray diffraction confirms that the C14 lattice remains intact through the intermediatetemperature regime up to 700 degrees C, followed by the gradual appearance of a BCC-type secondary phase in both alloys and additional sigma-phase reflections only in the Co-bearing alloy, while C14 reflections persist throughout. Together with post-annealing scanning electron microscopy/energy dispersive spectroscopy at 800 degrees C, this establishes diffusion-limited precipitation from a C14 matrix rather than a reconstructive C14 -> BCC transformation. The temperature evolution of a(T) and c(T) is weak in the C14-dominant regime and shows earlier deviations in the Co alloy, consistent with increased misfit and partitioning as secondary products develop. Magnetometry from 10 to 300 K indicates Curie-Weiss paramagnetism for both compositions with Curie-Weiss temperatures close to zero and large effective moments arising from multiple 3d species. Co addition markedly increases the low-temperature magnetization, consistent with the intrinsic Co 3d moment and its effect on the local 3d environment within the C14 matrix. Overall, Mn <-> Co substitution provides a practical route to tune the chemical stability of a C14 Laves backbone against BCC-type and sigma precipitation on heating while independently adjusting the magnetic response.

In light of breakthroughs in superconductivity under high pressure, and considering that record critical temperatures (T_cs) across various systems have been achieved under high pressure, the primary challenge for higher Tc should no longer solely be to increase T_c under extreme conditions but also to reduce, or ideally eliminate, the need for applied pressure in retaining pressure-induced or -enhanced superconductivity. The topological semiconductor Bi_0.5Sb_1.5Te_3 (BST) was chosen to demonstrate our approach to addressing this challenge and exploring its intriguing physics. Under pressures up to 50 GPa, three superconducting phases (BST-I, -II, and -III) were observed. A superconducting phase in BST-I appears at 4 GPa, without a structural transition, suggesting the possible topological nature of this phase. Using the pressure-quench protocol (PQP) recently developed by us, we successfully retained this pressure-induced phase at ambient pressure and revealed the bulk nature of the state. Significantly, this demonstrates recovery of a pressure-quenched sample from a diamond anvil cell at room temperature with the pressure-induced phase retained at ambient pressure. Other superconducting phases were retained in BST-II and -III at ambient pressure and subjected to thermal and temporal stability testing. Superconductivity was also found in BST with T_c up to 10.2 K, the record for this compound series. While PQP maintains superconducting phases in BST at ambient pressure, both depressurization and PQP enhance its T_c, possibly due to microstructures formed during these processes, offering an added avenue to raise T_c. These findings are supported by our density-functional theory calculations.

Introducing various n-type dopants into Mg3Sb2-based thermoelectric (TE) alloys significantly enhances their TE performance. However, the effect of excessive doping, particularly beyond the phase solubility limit, on the phase composition and microstructure remains underexplored. Here, we investigate the microstructure and TE performance of n-type Mg3-xMnx(Sb,Bi)(2) with Mn doping concentrations of 0.01 <= x <= 1.0. With low Mn doping (x < 0.1), Mn occupies both Mg sites and interstitials, suppressing Mg vacancies and increasing both the electrical conductivity from 8.6 x 10(4) to 11.3 x 10(4) S m(-1) and the power factor from 23.3 to 28.7 mu W cm(-1) K-2 at 300 K. At x = 0.01, a room-temperature figure of merit (zT) of 0.72 is achieved. Additionally, the lattice thermal conductivity decreases over the temperature range of 300-650 K due to enhanced phonon scattering, yielding a zT of 1.3 at 420 K and a peak zT of 1.74 at 573 K, as well as an average zT of 1.37, the highest reported for n-type Mg-3(Sb,Bi)(2) compounds over this temperature range. Moreover, a high conversion efficiency of 9.14% is achieved in a single-leg device at a temperature difference of 400 K, making this compound a promising candidate for low-grade waste heat recovery. With high Mn doping (x > 0.1), on the other hand, high-resolution transmission electron microscopy and selected area electron diffraction reveal the presence of Mn-rich secondary phases (e.g., Mn3Bi2, Mn2Sb, and MnSb) that act as electron-trapping centers, degrading TE performance and switching the n-type behavior to p-type. This study thus deepens our understanding of the relationships among dopant concentration, phase composition, microstructural evolution, and TE performance for Mg3Sb2-based TE alloys.

Time-domain thermoreflectance (TDTR) has been a standard technique for measuring thermal conductivity (κ) for more than 3 decades, yet its reliance on femtosecond lasers and metal transducers has limited its broader adoption in the materials community. Recent attempts to eliminate the metal layer have achieved partial success but have been hampered by dominant reflectance from photoexcited carriers, arising from the continued use of femtosecond pump and 800-nm probe pulses. Here, we introduce a nanosecond transducer-less TDTR (tl-TDTR) method that overcomes this challenge. Using ~80-ns pump pulses and a 450-nm continuous-wave probe, we suppress carrier-induced negative transients, yielding positive signals characteristic of pure thermoreflectance. Thermal conductivity is extracted via heat transport simulations and direct time-domain curve fitting. The method is validated on benchmark semiconductors (Si, Ge, InP) and cross-checked on Si and diamond using an Al-film transducer. Applied to cubic boron arsenide crystals, the technique reveals room-temperature κ exceeding 2,000 W/m·K—comparable to single-crystal diamond—and confirmed by traditional TDTR on the same samples. Raman, photoluminescence (PL), and PL lifetime measurements indicate high crystal quality. Sub-10-ns lifetimes remain shorter than expected for an indirect bandgap semiconductor, suggesting headroom for further κ improvement. The observed ~1/T2 temperature dependence indicates dominant 4-phonon scattering. Nanosecond tl-TDTR thus provides a rapid, nondestructive route to assess semiconductor thermal conductivity.

Cubic boron arsenide (c-BAs) has been theoretically predicted to exhibit thermal conductivity ąp̨p̨ą comparable to that of diamond, yet experimental measurements have plateaued at 1300W/mK. We report room-temperature ąp̨p̨ą exceeding 2000W/mK in c-BAs, on par with single-crystal diamond. This finding is enabled by high-quality single crystals and a newly developed nanosecond, transducer-less time-domain thermoreflectance technique that allows spatial mapping of ąp̨p̨ą without metal transducers. Thermal conductivity correlates with crystal quality, as evidenced by stronger photoluminescence and longer photoluminescence lifetimes. However, the observed nanosecond lifetimes remain shorter than expected for an indirect bandgap semiconductor, suggesting room for further crystal quality improvement and higher ąp̨p̨ą. These results challenge current theoretical models and highlight c-BAs as a promising material for next-generation electronics.

This study investigates the effects of 60 keV proton irradiation on BaTiO3-doped YBa2Cu3O7−δ (YBCO) films using masks with micron-scale holes to create controlled defect patterns aimed at enhancing superconducting properties. Contrary to expectations, masked irradiation resulted in a reduction in the critical current density (Jc), while unmasked irradiation demonstrated improvement, consistent with previous studies. Notably, no improvement was observed at 2 T around liquid nitrogen temperature. These observations highlight the challenges of employing micron-scale masks in defect engineering and underscore the need for further refinement to achieve the desired performance enhancement. Insights from this study contribute to advancing defect engineering techniques for improving YBCO’s performance in high-field applications, including fusion energy systems.