Understanding how complex systems transition between states requires mapping the energy landscape that governs these changes. Local transition-state networks reveal the barrier architecture that explains observed behaviour and enables mechanism-based prediction across computational chemistry, biology, and physics, yet in many practical settings current approaches either require pre-specified endpoints or rely on single-ended searches that provide only a limited sample of nearby saddles. We present a general optimization framework that systematically expands local coverage by coupling a multi-objective explorer with a bilayer minimum-mode kernel. The inner layer uses Hessian-vector products to recover the lowest-curvature subspace, the outer layer optimizes on a reflected force to reach index-1 saddles, then a two-sided descent certifies connectivity. The GPU-based pipeline is portable across autodiff backends and eigensolvers and, on large atomistic-spin tests, matches explicit-Hessian accuracy while cutting peak memory and wall time by orders of magnitude. Applied to a DFT-parameterized Néel-type skyrmionic model, it recovers known routes and reveals previously unreported mechanisms, including meron-antimeron-mediated Néel-type skyrmionic duplication, annihilation, and chiral-droplet formation, enabling up to 32 pathways between biskyrmion ( Q = 2) and biantiskyrmion ( Q = −2). The same core transfers to Cartesian atoms, automatically mapping canonical rearrangements of a Ni(111) heptamer, underscoring the framework’s generality.

Magnonics promises low-dissipation information processing, yet spin-polarized magnon transport requires magnetic fields or spin–orbit couplings. Altermagnets exhibit spin-polarized electronic states and zero net magnetization. However, achieving large magnon spin splitting and robust magnonic spin currents remains challenging. Here we show that twisted van der Waals antiferromagnets provide a symmetry-tunable platform for the altermagnetic magnons. Alternating intralayer exchange arises in twisted bilayers lacking inversion and horizontal mirror symmetries, rendering nonrelativistic magnon spin splitting. Breaking out-of-plane rotational symmetries of a constituent monolayer significantly enhances low-energy splittings. We illustrate general conclusions in twisted CrPS₄ (d-wave) and CrI₃ (i-wave) bilayers. Moreover, pronounced field-free spin currents, characterized by robust spin Seebeck and spin Nernst effects, emerge in CrPS₄. Remarkably, the spin transport is efficiently tuned by twist angle and exceeds that of conventional altermagnets by orders of magnitude. Our work provides novel insights into controlling magnons, deepening our fundamental understanding of altermagnetic spintronics.

Recent advances in both theoretical and experimental techniques have dramatically expanded our ability to probe and model ultrafast demagnetization, covering magnetization dynamics from the femtosecond to the tens-of-picosecond regime. It is now well established that at the very shortest timescales, coherent electron dynamics dominates the response to an ultrafast excitation, whereas on picosecond timescales the dynamics are accurately captured by atomistic descriptions of the spin system. Correspondingly, real-time time-dependent density functional theory (rt-TDDFT) provides a quantitative framework for the coherent femtosecond regime, while atomistic Landau–Lifshitz–Gilbert or Landau–Lifshitz–Bloch models describe the subsequent thermal spin evolution at the picosecond scale. A central challenge is to develop a unified multiscale description that accurately captures the intermediate nonthermal regime while providing seamless handshakes to the coherent electron dynamics regime of the femtosecond timescale and the thermally driven spin dynamics regime of the picosecond timescale. The intermediate regime is characterized by strongly out-of-equilibrium electron, magnon, and phonon populations, together with rapid exchange of energy and angular momentum between them. In the present work, this problem is discussed and several approaches to modeling the intermediate regime are highlighted, including density-matrix methods, quantum kinetic theory, and nonequilibrium Green's functions. Particular attention is given to a Boltzmann transport formulation combined with T-matrix spin-fluctuation theory, which may provide a practical route toward a fully band- and channel-resolved description of electron, magnon, and phonon scattering. Such a framework could contribute toward connecting the coherent rt-TDDFT description at early times to atomistic spin dynamics in the thermal regime, thereby providing a multiscale route toward predictive modelling of ultrafast magnetization dynamics across timescales.

Unconventional antiferromagnets combine zero net magnetization with spin-split electronic bands, offering a distinct, important platform for spintronics. Their discovery, however, has so far depended largely on case-by-case studies and on a limited number of compounds with experimentally resolved magnetic structures. Here, we overcome these bottlenecks by resolving magnetic ground states across a broad materials database. We narrow down 37163 magnets from the Materials Project to 189 collinear antiferromagnets by combining physics-informed prescreening high-throughput exchange calculations, and Luttinger–Tisza analysis. Among these, symmetry analysis identifies 36 altermagnets and 11 Luttinger-compensated ferrimagnets (LCFs), including 22 altermagnets and 9 LCFs that have not been reported previously. The identified unconventional antiferromagnets can support nonrelativistic spin Hall effects and doping-tunable spin transport with switchable polarization and giant anisotropy. Our framework converts broad structural databases into a curated, symmetry-classified set of experimentally testable compensated spin-split magnets, establishing a scalable route for the efficient discovery of functional antiferromagnets.

High-pressure (HP) electrical resistivity measurements of superconducting quasi-skutterudite Y5Rh6Sn18 single crystals were conducted up to 10.7 GPa using a diamond anvil pressure cell. Additionally, HP synchrotron X-ray powder diffraction (XRPD) studies were performed on Y5Rh6Sn18 up to 8 GPa and Sc5Rh6Sn18 up to 11.7 GPa, along with HP Raman spectroscopy. At ambient conditions, the Y5Rh6Sn18 single crystal shows an onset 3.60 K, which increases to a maximum of 3.94 K at 7.89 GPa. Beyond this pressure, further increases lead to a slight decline in Tc. Furthermore, the bad metal nature of the Y5Rh6Sn18 single crystal is suppressed by external pressure, with the residual resistivity ratio (RRR) value increasing from 0.77 to 0.92. The activation energy for electric conduction (Ea) decreases from 2.74 meV at 0.62 GPa to 0.39 meV at 10.65 GPa, indicating enhanced metallic behaviour. Additionally, four Raman vibrational modes are observed, which exhibit a smooth blue shift with increasing pressure up to 9.6 GPa, similar to that of its sister compound Sc5Rh6Sn18. Both Y5Rh6Sn18 and Sc5Rh6Sn18 crystallize in the tetragonal I41/acd space group. With increasing external pressure up to 7 GPa, these compounds exhibit a smooth reduction in unit-cell volume without any structural phase transitions, as described by a second-order Birch-Murnaghan equation of state. Above 7 GPa, Sc5Rh6Sn18 also shows an upturn in both lattice parameters a and c and unit cell volume, while an upturn in only the lattice parameter c (and consequently on unit cell volume) is observed for Y5Rh6Sn18 at 7 GPa. The deviation in the lattice parameter at higher pressure in Y5Rh6Sn18 seems to correlate with the observed decline in Tc with pressure. First-principles calculations under pressure reveal a moderate increase in the density of states (DOS) up to ~ 10 GPa, followed by a slight decrease for higher pressures, a trend which is similar to the observed critical temperature. Furthermore, from theory it is clear that the structure remains stable up to approximately 30 GPa.

Shake-up phenomena, rooted in the sudden approximation and many-body quantum dynamics, unveil critical characteristics of quantum systems, with wide-ranging applications in molecular spectroscopy and electronic structure studies. Here, this principle is extended to magnetic systems, and magnon shake-up structures and their relevance in generating and sensing magnon-magnon entanglement are demonstrated. This not only reveals new insights into shake-up phenomena and quantum magnetism but also paves the way for new opportunities in quantum technologies.

In this study, we employ ab initio density functional theory (DFT) calculations to elucidate the microscopic origin of the Jahn–Teller distortion suppression and magnetic moment quenching in LiNiO₂ (LNO) during delithiation. Our results reveal that these effects arise not from changes in the Ni oxidation state but from an electronic charge redistribution between the e_g and t_2g​ orbitals derived from Ni–3d states. This internal electronic rearrangement, driven by strong hybridization between Ni–3d and O–2p orbitals, accounts for the inactivation of the Jahn–Teller distortion and the quenching of the magnetic moment at the NiO₆ octahedra. The same mechanism also explains the shifts observed in the Ni and O K-edge X-ray absorption near-edge structure (XANES) spectra during delithiation. Our findings provide a new microscopic interpretation of the LNO redox process, highlighting the role of electron redistribution within the Ni–3d manifold as the true origin of its structural and magnetic transformations.

We investigate the pressure evolution of charge density wave (CDW) order in the intermetallic compound BaFe2Al9, which undergoes a pronounced first-order CDW transition 112 K at ambient pressure. High-pressure electrical resistivity and magnetization measurements reveal a systematic enhancement of the CDW transition temperature (TCDW) at a rate of 60 K/GPa, reaching 300 K under 3.2 GPa. The transition sharpness diminishes with pressure, indicating a crossover from first- to secondorder behavior. Fermi liquid (FL) fits to the low-temperature resistivity reveal an increase in residual resistivity and a nonmonotonic evolution of the FL coefficient, indicating a pressure-induced Fermi surface (FS) reconstruction. Synchrotron x-ray diffraction reveals anisotropic lattice compression, a change in the compression trend of lattice parameters, and an abrupt change in microstrain at 3.6GPa. Density functional theory calculations reveal pressure-induced flattening of quasi-two-dimensional FS sheets associated with the CDW nesting vector, consistent with enhanced nesting. These findings highlight the critical role of lattice strain and electronic structure evolution in stabilizing a high-temperature CDW phase, making BaFe2Al9 a rare example of a three-dimensional material where pressure promotes rather than suppresses the CDW order.

We investigated the element-specific electronic structure and charge-carrier dynamics of a single-crystal ferromagnet CoS2 with complementary x-ray spectroscopy techniques. Hard x-ray photoemission (HAXPES) is used to provide crucial information on the bulk electronic structure and chemical bonding in CoS2 that is compared against the isoelectronic paramagnet CoSe2. The Co 1⁢𝑠 core-level line shows several satellite features for CoS2, showing explicit charge-transfer processes and local screening of the core hole by S ligands, whereas no such features are observed in CoSe2. The satellite structures indicate the electronic configuration of divalent Co2+ as a combination of 𝑑8⁢Ḻ and 𝑑9⁢Ḻ2 in addition to the nominal ionic 𝑑7 state, where Ḻ represents an S 3⁢𝑝 hole. We employ resonant Auger spectroscopy across the S 𝐾-edge for CoS2 to obtain electron delocalization times to adjacent Co atomic sites. The fast carrier dynamics are attributed to strongly screened Coulomb interactions and hence a facile carrier delocalization. The strong hybridization formed between the Co 3⁢𝑑 and S 3⁢𝑝 states with pronounced charge-transfer character reflects a self-doped system with a finite density 𝑛 of holes at the sulfur site (Ḻ𝑛), in line with recent models that indicate a negative charge-transfer energy for CoS2. In addition to HAXPES data, we also report on experimental and theoretical 𝐿-edge x-ray absorption and x-ray magnetic circular dichroism data for CoS2 that demonstrate multiconfiguration effects in the excitation process. To enable a direct comparison of the experimental spectra, we used density functional theory calculations to obtain the projected density of states to describe the ground-state electronic structure. The existence of fast carrier dynamics and strong charge-transfer properties, demonstrated in this study, highlights the unique nature of CoS2 with a wide potential in topological spintronics applications and integration in energy-related device platforms.

The ability to efficiently control topological magnetism is crucial for advancing technological applications and deepening our understanding of magnetic systems. Although emerging van der Waals (vdW) multiferroics present a promising frontier for energy-efficient spin manipulation, the control of topological magnetism remains challenging due to its scarcity in multiferroics. Here, we demonstrate that highly tunable merons and antimerons emerge in monolayer multiferroic CuCrP₂S₆ (CCPS). The antiferroelectric-to-ferroelectric (AFE-FE) transition enhances exchange couplings, notably reducing meron density and increasing meron size during cooling. Merons exhibit unique dynamics, characterized by nontrivial attraction and annihilation processes, which generates distinct long-lived spin waves and reduces meron number difference between AFE and FE phases until they vanish. Importantly, ultrafast laser pulses can induce ferroelectricity-tunable merons from a uniform in-plane magnetization, re-leading to a large difference in meron density between the AFE and FE phases. These findings enhance our understanding of topological magnetism and open up exciting avenues for controlling the properties and dynamics of topological states through electrical and optical methods.