We perform time-resolved magneto-optical Kerr effect measurements and record the magnetization dynamics for external magnetic fields along various symmetry axes of the chiral magnet MnSi. The different orientations of the magnetic field result in very different magnetization dynamics. For magnetic fields along the a-b plane, we observe rapid oscillations assigned to magnon modes. These oscillations are detected for various external magnetic fields and are well reproduced by our theoretical spin-wave calculations. When applying magnetic fields at 45 degrees with respect to the a-b plane and along the c axis, changes in the net magnetization are instead observed. In the absence of external magnetic fields, the net magnetization is zero, and light-induced magnetization is observed. First-principles calculations identify the inverse Faraday effect as the mechanism leading to the observed light-induced magnetization. When sufficiently strong external magnetic fields are applied off the a-b plane, the MnSi crystal is brought into a ferromagnetic phase, where the laser pulse's demagnetizing effect is observed. This observation suggests that by changing the strength or orientation of the external magnetic field the MnSi crystal can be magnetized or demagnetized using a laser pulse.

Two-dimensional materials that combine ferroelectric and ferromagnetic orders could exhibit a range of exotic physical properties and find use in applications such as energy-efficient spintronics. However, long-range ferroic orders in two dimensions are prone to destruction. For example, depolarization fields can destabilize ferroelectric order and thermal fluctuations can suppress magnetic order. Here we report multiferroic van der Waals heterostructures made from atomic layers of ferroelectric CuCrP2S6 and ferromagnetic Fe3GeTe2. We demonstrate reversible, non-volatile ferroelectric control of the magnetic anisotropy of two-dimensional Fe3GeTe2, and with this, probe the interferroic magnetoelectric coupling. Polarization switching of CuCrP2S6 changes the magnetic coercivity of a 3.8-nm-thick Fe3GeTe2 layer by approximately 14 mT at a testing temperature of 153 K, with a control efficiency around 65

The crystal structure and properties of CrAu3Sb6 are presented, determined by measurements on single crystal and polycrystalline samples and first-principles calculations. The trigonal structure (space group P3̅1m) comprises a CdI2-like sublattice of AuSb2 with Cr occupying octahedral holes in a fully ordered triangular array. It can be viewed as a variation of the interesting and well-known families of partially intercalated transition metal dichalcogenides, but with stronger interactions along the stacking direction evidenced by short Cr-Au distances. The compound is metallic and ferromagnetic with a Curie temperature of 164 K. A strong anomalous contribution to the Hall effect is seen in the ferromagnetic state, and quantum oscillations are observed in magnetization at 2 K. Magnetization measurements show that the ordered moments of 1.5 μB per Cr are oriented along the c-axis with relatively strong magnetocrystalline anisotropy. Electronic structure calculations confirm this uniaxial anisotropy and the important role of spin-orbit coupling in CrAu3Sb6 and reveal strongly favored ferromagnetic ground state consistent with the measured Curie temperature. Through combined experiment and theory, this work provides a detailed picture of the basic properties and behaviors of this uniquely structured, Cr-based, anisotropic ferromagnet.

The high-entropy perovskite Eu(Sc/Cr/Fe/Ni/Al)O3 was investigated to explore its multifunctionality and correlated behavior. Special Quasirandom Structure (SQS)-based X-ray Pair Distribution Function (PDF) analysis reveals anomalously short Eu-Ni and long Ni–O distances, explained by an electrostatic leaning of Ni cations toward Eu at the ground state with bond-valence analysis predicting the coexistence of Ni2+, Cr3+ and Cr4+. Temperature-dependent X-ray diffraction analysis reveals continuous unit-cell contraction upon cooling, with anomalous features near 140 K, accompanied by peak broadening—indicating structural change. AC phase-angle features suggest changes in the dielectric constants at 260 K and 140 K, indicating polaronic transport. The derivative heat capacity below 130 K, likely associated with ordering of the disproportionated magnetic sublattices. Photoluminescence spectra reveal marked intensity quenching below 150 K, possibly-due to the suppression of Cr3+ emission. These results cumulatively suggest a cooperative charge ordering or disproportionation below 140 K.

Multilayer graphene with different stacking sequences has emerged as a powerful setting for correlated and topological phases. In parallel, progress in graphene heterostructures with magnetic or correlated materials-most notably the Kitaev candidate alpha - RuCl3-has demonstrated charge transfer, magnetic proximity effects, and interfacial reconstruction, creating new opportunities for engineered quantum systems. Motivated by these developments, we explore a three-dimensional analog in which alpha - RuCl3 layers are inserted directly into the van der Waals gaps of graphite, forming an intercalated system. Here, we report the successful synthesis and comprehensive characterization of graphite intercalated with alpha - RuCl3. Using a combination of X-ray diffraction, quantum oscillation measurements, scanning transmission electron microscopy and first-principles electronic structure calculations, we study the structural and electronic properties of this intercalated crystals. Our results demonstrate that graphite intercalated with alpha - RuCl3 offers a robust route to develop three-dimensional materials with access to novel correlated and topological states.

We identify a correlation-driven mechanism for the temperature-induced spin reorientation in the quasi-one-dimensional van der Waals antiferromagnet CrPS4. Magnetic pair distribution function (mPDF) analysis resolves the local spin direction and shows that ferromagnetic intrachain correlations persist far above TN. Combining these correlations with a DFT-derived spin Hamiltonian reveals competing single-ion and exchange-anisotropy channels, with single-ion anisotropy remaining local while exchange anisotropy is renormalized as intersite correlations decay. This differential renormalization rotates the effective easy axis and captures the ordered-state canting. Above TN, the continued rotation beyond the model prediction delineates the limits of the dominant-chain approximation. These results establish mPDF-derived correlations as direct inputs to microscopic Hamiltonians and show how low-dimensional correlations can control magnetic anisotropy.

α-RuCl3 has emerged as a possible candidate for a quantum spin liquid (QSL) that promises exotic quasiparticles relevant for fault-tolerant quantum computation. Here, we report spin-sensitive transport measurements using a proximal spin Hall metal, platinum (Pt), to probe magnetic moments in the insulator α-RuCl3. We observe spin Hall magnetoresistance (SMR), where both the transverse and longitudinal resistivities exhibit angular oscillations between the in-plane magnetic field and the current, driven by the interplay between the spin Hall effect in Pt and local magnetic moments in α-RuCl3. These oscillations occur from 1.5 to 18 T, covering the zigzag antiferromagnetic, putative QSL, and supposedly partially field-polarized phases. The phase of the SMR oscillations suggests that the local moments, whether static or fluctuating, develop spin anisotropy with a quantization axis in-plane and largely transverse to the magnetic field across all fields from 1.5 to 18 T. Temperature dependence indicates that the spin anisotropy operates at an energy scale similar to that of the reported QSL signatures in α-RuCl3.

Multiferroic tunnel junctions (MFTJs) represent a class of multistate, non-volatile spintronic devices, in which electron tunnelling can be manipulated by switching long-range lattice and spin orders. In contrast to conventional oxide-based MFTJs, MFTJs constructed from two-dimensional van der Waals (vdW) crystals promise minimal defect concentration in the constituents and at interfaces, which may allow for probing intrinsic tunnelling physics and the development of high-performance devices. Here we construct Fe3GeTe2/CuInP2S6/Fe3GeTe2 all-vdW MFTJs by assembling multilayer flakes of ferromagnetic Fe3GeTe2 electrodes and a ferroelectric CuInP2S6 spacer. These MFTJs exhibit four non-volatile resistance states featuring sizable tunnelling magnetoresistance of ∼102% and tunnelling electroresistance of ∼104%. To tune the properties of the vdW MFTJ, we make use of the flexibility in material choice offered by vdW heterostructure devices; we use Fe3GeTe2/Fe5GeTe2 asymmetric electrodes to boost the tunnelling electroresistance by 103%, we integrate In2Se3 as a ferroelectric with a smaller bandgap to enhance the ON-state current density by 104% to 104 A cm-2 and we use Fe3GaTe2 electrodes to demonstrate room temperature operation. Furthermore, when we combine the asymmetric ferromagnetic electrodes with the small-bandgap ferroelectric spacer to construct Fe3GeTe2/In2Se3/Fe5GeTe2 MFTJs, we simultaneously realized tunnelling electroresistance of 106% and an ON-state current density of 104 A cm-2, both two orders of magnitude higher than the highest values achieved with conventional oxide-based MFTJs. In the future, our all-vdW MFTJs with the tailorability of all functional layers may make it possible to investigate fundamental aspects of interlayer tunnelling and enable the design of functional magnetoelectric nanodevices.

The intricate interplay between flat bands, Dirac cones, and magnetism in kagome materials has recently attracted significant attention from materials scientists, particularly in compounds belonging to the RMn6Sn6 family (R = Sc, Y, rare earths), due to their inherent magnetic frustration. Here, we present a detailed investigation of the ferromagnetic (FM) kagome magnet ScMn6(Sn0.78Ga0.22)6 using angle-resolved photoemission spectroscopy (ARPES), magnetotransport measurements, and density functional theory (DFT) calculations. Our findings reveal a paramagnetic-to-FM transition at 375 K, with the in-plane direction serving as the easy magnetization axis. Notably, ARPES measurements reveal a Dirac cone near the Fermi energy, while the Hall resistivity exhibits a substantial contribution from the anomalous Hall effect. Additionally, we observe a flat band spanning a substantial portion of the Brillouin zone, arising from the destructive interference of wave functions in the Mn kagome lattice. Theoretical calculations reveal that the gap in the Dirac cone can be modulated by altering the orientation of the magnetic moment. An out-of-plane orientation produces a gap of approximately 15 meV, while an in-plane alignment leads to a gapless state, as corroborated by ARPES measurements. This comprehensive analysis provides valuable insights into the electronic structure of magnetic kagome materials and paves the way for exploring novel topological phases in this material class.

Is it feasible to alter the ground-state properties of a material by engineering its electromagnetic environment? Inspired by theoretical predictions1-12, experimental realizations of such cavity-controlled properties without optical excitation are beginning to emerge13-19. Here we devised and implemented a new platform to realize cavity-altered materials. Single crystals of hyperbolic van der Waals (vdW) compounds provide a resonant electromagnetic environment with enhanced density of photonic states and prominent mode confinement20-24. We interfaced hexagonal boron nitride (hBN) with the molecular superconductor κ-(BEDT-TTF)2Cu[N(CN)2]Br (κ-ET). The frequencies of infrared hyperbolic modes (HMs) of hBN (refs. 25,26) match the infrared-active carbon-carbon (C=C) stretching molecular resonance of κ-ET implicated in superconductivity27. Nano-optical data supported by first-principles molecular Langevin dynamics simulations confirm the presence of resonant coupling between the hBN hyperbolic cavity modes and the C=C stretching mode in κ-ET. Meissner-effect measurements using magnetic force microscopy (MFM) demonstrate a strong suppression of superfluid density near the hBN/κ-ET interface. Non-resonant control heterostructures, including RuCl3/κ-ET and hBN/Bi2Sr2CaCu2O8+x (BSCCO), do not show the pronounced superfluid suppression. These observations suggest that hBN/κ-ET realizes a cavity-altered superconducting ground state. Our work highlights the potential of dark cavities devoid of external photons for engineering electronic ground-state properties of complex quantum materials.

Nematicity, where rotational symmetry of the crystal lattice is spontaneously broken, is a ubiquitous phenomenon in correlated quantum matter, often intertwining with other orders to produce a richer spectrum of phases. Here we report a new phase transition in high-quality ScV6Sn6 bilayer kagome metal at a temperature T^*, occurring seven Kelvins below the charge density wave (CDW) transition at T_CDW, as indicated by thermodynamic, transport, and optical measurements. This emerging intermediate phase does not exhibit spontaneous time-reversal-symmetry breaking, as evidenced by zero-field Sagnac interferometer experiments. However, it displays a strong, spontaneous (strain- and field-free) anisotropy in the kagome plane between T^* and T_CDW, as revealed by transport and optical polarization rotation measurements. Additionally, a pronounced depolarization effect detected by the Sagnac interferometer further confirms its nematic nature. This intermediate nematic phase, alongside the recently discovered intra-unit cell nematic order at much lower temperatures, presents a diverse landscape of nematicities at multiple length and temperature scales, distinguishing it from those observed in kagome metals AV3Sb5. Our findings highlight ScV6Sn6 and the broader RM6X6 intermetallic family as fertile platforms for realizing symmetry-breaking phases driven by a unique interplay of competing CDW instabilities, kagome physics, and Van Hove singularities.

Two-dimensional layered materials, where magnetic layers are linked through van der Waals (vdW) bonding provides a promising platform for spintronics applications and quantum behavior. However, realizing their full potential requires a deeper understanding of their spin behavior across different length scales. In this study, we investigated the local magnetic correlations of bulk antiferromagnetic vdW materials MnPSe3, MnPS3 and CrPS4 using neutron scattering using the magnetic pair distribution function (mPDF) technique. We explore short-range magnetic correlations in a systematic series of MnPSxSe3-x (x=0, 1, 1.5, 2,3) powder samples with neutron total scattering data. Our results reveal that substituting S/Se anions, despite being non-magnetic, tunes both atomic structure and enables the gradual modulation of magnetic correlation length and spin angle. Complementary inelastic neutron scattering measurement further quantify changes in the magnetic exchange interactions, highlighting the continuous evolution of spin correlations across the series. Additionally, short-range magnetic correlations of CrPS4 were analyzed and modeled using the mPDF technique in the paramagnetic regime, under both zero-field and applied magnetic field conditions.

Complex chalcogenides are renowned for their tunable electronic, magnetic, and optical properties under external stimuli. The MPX3 family (M = Mn, Ni, Co, V; X = S, Se) is a platform for many exciting discoveries—especially under compression—although CdPS3 is thought to be different because the Cd center possesses a filled 4d shell, which precludes Mottness. Here, we combine synchrotron-based infrared absorbance and Raman scattering spectroscopies with diamond anvil cell techniques, complementary lattice dynamics calculations, and an analysis of the energy landscape to reveal a series of structural phase transitions in CdPS3. We find four distinct pressure-driven transitions, with low frequency modes detectable over the full 35 GPa range of our investigation. A group–subgroup analysis along with our first-principles calculations allows us to partially unravel the space group sequence. For instance, the first critical pressure is a monoclinic C2/m to trigonal R3̄ transition at 10 GPa. Despite the softness and overall sensitivity to pressure, we do not locate an insulator-to-metal transition in this pressure range, indicating that the energy scale for gap closure is significantly higher than expected. We discuss these findings in terms of force-induced color change and Mott vs band character in this system.

The kagome lattice ferromagnet, Co 3 Sn 2 S 2 , serves as template for a host of materials that exhibit exotic topological states, as well as a giant anomalous Hall state—a momentous realization in condensed matter physics. The anisotropic exchange interactions are probed by applying external magnetic fields in various directions along major crystal axes and the magneto‐optical response is recorded. When magnetic fields are applied along the a–b plane, long‐range magnetism forms and grows with increasing temperature. This counterintuitive behavior does not take place when the magnetic field is applied at a slight angle off the a–b plane. In fact, the opposite effect is observed for this exact configuration, as well as for other fields arrangements. Ab initio theoretical calculations reveal that anisotropic exchange interactions are the underlying mechanism leading to this peculiar behavior. Furthermore, the long‐range ferromagnetic order along the c ‐axis is thought to coexist with an antiferromagnetic, or spin glass, state in the a–b plane, before becoming paramagnetic above the Curie temperature ( T c ). These two coexisting magnetic states are thought to compete as the temperature approaches T c , with the antiferromagnetic state gaining strength compared to the ferromagnetic order.

The magnetic insulator α-RuCl 3 is proximate to a quantum spin liquid (QSL) [1] described by the Kitaev model [2]. A promising route to realizing a true Kitaev QSL in α-RuCl 3 is to reduce its dimensionality via mechanical exfoliation. In addition to enhancing magnetic fluctuations, exfoliating α-RuCl 3 opens the door to manipulating its magnetic state by coupling it to other two-dimensional materials. However, measuring the magnetic properties of such small samples represents a great technical challenge. Moreover, to harness the technological potential of this predicted Kitaev QSL phase and its non-Abelian anyonic excitations, an electrical probing technique is highly desirable but limited by the insulating nature of the material. Here, we present angle-dependent tunneling magnetoresistance (TMR) measurements on ultrathin α-RuCl 3 crystals with various layer numbers (Fig. 1) to probe their magnetic, electronic and crystal structure [3]. We observe a giant change in resistance – as large as ∼ 2500 % – when the magnetic field rotates either within or out of the α-RuCl 3 plane. This is a manifestation of the anisotropic spin interactions arising from the strong spin-orbit coupling in this material. Using TMR as a probe, we track the magnetic phase diagram of α-RuCl 3 as a function of temperature, applied magnetic field and its angle relative to the crystallographic axes. Our results show that few-layer α-RuCl 3 hosts a zigzag antiferromagnetic order with a Néel temperature of ~ 14 K, higher than the ~ 7 K measured in bulk samples with a rhombohedral stacking. We explain this surprising result by showing that exfoliated flakes maintain a monoclinic structure at low temperature, while bulk α-RuCl 3 is believed to undergo a monoclinic-to-rhombohedral phase transition. This conclusion is supported by our scanning transmission microscopy study of isolated flakes. Our study provides a deeper understanding of how the magnetic properties of α-RuCl 3 depend on its stacking order and layer number, which helps lay the groundwork for the van der Waals engineering of exotic magnetic phases such as QSLs. References [1] Takagi, H., Takayama, T., Jackeli, G., Khaliullin, G. & Nagler, S. E. Nat. Rev. Phys . 1 , 264–280 (2019). [2] Kitaev, A. Ann. Phys. 321, 2-111 (2006). [3] Massicotte, M. et al . ACS Nano , 18 , 25118–25127 (2024). Figure 1. Schematic representation of a graphite/α-RuCl 3 /graphite magnetic tunnel junction Figure 1

The kagome motif is a versatile platform for condensed matter physics, hosting rich interactions between magnetic, electronic, and structural degrees of freedom. In recent years, the discovery of a charge density wave (CDW) in the AV(3)Sb(5) superconductors and structurally-derived bond density waves (BDW) in FeGe and ScV6Sn6 have stoked the search for new kagome platforms broadly exhibiting density wave (DW) transitions. In this work, we evaluate the known AM(6)X(6) chemistries and construct a stability diagram that summarizes the structural relationships among the >125 member family. Subsequently, we introduce our discovery of the broader LnNb(6)Sn(6) (Ln:Ce-Nd,Sm,Gd-Tm,Lu,Y) family of kagome metals and an analogous DW transition in LuNb6Sn6. Our X-ray scattering measurements clearly indicate a (1/3, 1/3, 1/3) ordering wave vector (3x3x3 superlattice) and diffuse scattering on half-integer L-planes. Our analysis of the structural data supports the "rattling mode" DW model proposed for ScV6Sn6 and paints a detailed picture of the steric interactions between the rare-earth filler element and the host Nb-Sn kagome scaffolding. We also provide a broad survey of the magnetic properties within the HfFe6Ge6-type LnNb(6)Sn(6) members, revealing a number of complex antiferromagnetic and metamagnetic transitions throughout the family. This work integrates our new LnNb(6)Sn(6) series of compounds into the broader AM(6)X(6) family, providing new material platforms and forging a new route forward at the frontier of kagome metal research.

The study of magnetoresistance (MR) phenomena has been pivotal in advancing magnetic sensors and spintronic devices. Helimagnets present an intriguing avenue for spintronics research. Theoretical predictions suggest that MR magnitude in the helimagnetic (HM) regime surpasses that in the ferromagnetic (FM) regime by over an order of magnitude. However, in metallic helimagnets like MnP, MR in the HM phase remains modest (<10%), limiting its application in MR devices. Here, a groundbreaking approach is presented to achieve a giant low-field MR effect in nanostructured MnP by leveraging confinement and strain effects along with spin helicity. Unlike the modest MR observed in bulk MnP single crystals and large-grain polycrystalline films, which exhibit a small negative MR in the FM region (∼2%) increasing to ∼8% in the HM region across 10-300 K, a grain size-dependent giant positive MR (∼90%) is discovered near FM to HM transition temperature (TN ∼ 110 K), followed by a rapid decline to a negative MR below ∼55 K in MnP nanocrystalline films. These findings illuminate a strain-mediated spin helicity phenomenon in nanostructured helimagnets, presenting a promising pathway for the development of high-performance MR sensors and spintronic devices through the strategic utilization of confinement and strain effects.

The density waves that develop in kagome metals ScV6Sn6 and LuNb6Sn6 at low temperature appear to arise from underfilled atomic columns within a V-Sn or Nb-Sn scaffolding. Compressing this network with applied pressure in ScV6Sn6 suppressed the structural transition temperature by constraining atomic rattling and inhibiting the shifts that define the structural modulation. We predicted that the density wave transition in LuNb6Sn6 at 68 K would be suppressed by pressure as well. In this Letter, we examine the pressure dependence of the density wave transition by measuring resistance vs temperature up to 2.26 GPa. We found the transition temperature is smoothly depressed and disappears around 1.9 GPa. This result not only addresses our prediction, but strengthens the rattling chains origin of structural instabilities in the HfFe6Ge6-type kagome metals.

We present a comprehensive investigation of the kagome metal LuV6Sn6 through magnetotransport and torque magnetometry studies in magnetic fields up to 41 T and temperatures as low as 0.3 K. Magnetoresistance measurements up to 31 T reveal clear Shubnikov-de Haas (SdH) oscillations with two dominant frequency peaks: F-alpha = 12 T and F-beta = 155 T. The Berry phase Phi(B), calculated from Landau level fan diagrams, indicates a nontrivial topology for both the alpha- and beta-orbits. To explore the possibility of higher-frequency signals in LuV6Sn6, we employed another technique: torque magnetometry. Torque measured with applied fields up to 41 T reveals clear de Haas-van Alphen (dHvA) oscillations, with frequency signals as high as 10 kT. Angular and temperature-dependent quantum oscillation measurements allowed us to extract the effective mass of charge carriers and map the Fermi surface of LuV6Sn6. To complement the experimental findings, we performed electronic band structure and Fermi surface calculations. The electronic bands of LuV6Sn6 reveal intriguing features, including flat bands, van Hove singularities, and Dirac points near the Fermi level. Two bands cross the Fermi level, contributing a deformed cylindrical shape at the Gamma-point and small chainlike Fermi surfaces near the Brillouin zone boundaries. Theoretical quantum oscillation frequencies derived from Fermi surface cross-sectional areas align well with experimental SdH and dHvA results. These combined experimental and theoretical insights provide a deeper understanding of the electronic structure of LuV6Sn6 and establish the foundation for exploring electronic properties in other vanadium-and titanium-based kagome systems.