We investigate magnetotransport in exfoliated nanostructures of the candidate magnetic 3D topological insulator $\mathrm{EuSn_{2}As_{2}}$. Similar to macroscopic single crystals, the negative magnetoresistance observed below the Néel temperature ($T_N$ = 24 K) is related to the canted antiferromagnetic state (CAF) of an easy-plane antiferromagnet (AFM), with an increase of the saturation field when tilting the applied magnetic field away from the (ab) plane ($μ_{0} H^{c}_{s}$ = 4.9 T, $μ_{0} H^{ab}_{s}$ = 3.6 T). Higher-accuracy measurements in nanostructures up to 14 T further evidence a non-linear normal Hall response due to several electronic bands. Interestingly, the transverse resistance due to magnetism reveals an anomalous Hall effect in the CAF state, but also a topological Hall effect due to chiral spin textures, as found in AFM or helical magnets. The presence of real-space chiral spin texture, already reported in another magnetic topological insulator, $\mathrm{MnBi_{2}Te_{4}}$, could be a characteristic generally appearing in magnetic 3D topological insulators.

Twisted multilayers of two-dimensional materials attract widespread research interest due to their intriguing electronic and optical properties related to their chiral symmetry breaking and moir & eacute; effects. The two-dimensional transition metal dichalcogenide MoSe2 is a particularly promising material for twisted multilayers, capable of sustaining moir & eacute; excitons. Here, we report on a rational bottom-up synthesis approach for twisted MoSe2 flakes by chemical vapor transport (CVT). Screw dislocation-driven growth was forced by surface-fused SiO2 nanoparticles on the substrates that serve as potential nucleation points in low supersaturation condition. Thus, crystal growth by in-situ CVT under addition of MoCl5 leads to bulk 2H-MoSe2 in a temperature gradient from 900 to 820 degrees C with a dwell time of 96 h. Hexagonally shaped 2H-MoSe2 flakes were grown from 710 to 685 degrees C with a dwell time of 30 min on SiO2@Al2O3(0001) substrates. Electron backscatter diffraction as well as electron microscopy reveals the screw dislocation-driven growth of triangular 3R-MoSe2 with individual step heights between 0.9 and 2.9 nm on SiO2@Si(100) under the same conditions. Finally, twisted MoSe2 flakes exhibiting a twist angle of 19 degrees with respect to the [010] zone axis could be synthesized.

The discovery of chiral helical magnetism (CHM) in Cr1/3NbS2 and the stabilization of a chiral soliton lattice has attracted considerable interest in view of their potential technological applications. However, there is an ongoing debate regarding whether the sister compound, Mn1/3NbS2, which shares the same crystal structure, exhibits similar nontrivial properties which likewise rely on the lack of inversion symmetry at the magnetic ion. In this study, we conduct a comprehensive investigation of the magnetically ordered states of both compounds, using Cr-53, Mn-55, and Nb-93 NMR. Our results, supported by density-functional calculations, detect in a highquality single crystal of Cr1/3NbS2 all the signatures of the monoaxial CHM in a magnetic field, identifying it as a reference case for NMR. The detailed understanding of this prototypic behavior provides a reference for Mn1/3NbS2. Despite the much larger density of specific defects in this second material, we confirm the presence of a CHM phase in the Mn compound, characterized by a very large critical field for the forced ferromagnetic phase (approximate to 5 T for the applied field along c).

Excitonic quasiparticles and their interactions with phonons, magnons, and charge carriers may play a pivotal role in governing the optical properties and their correlation with magnetic interactions in two‐dimensional (2D) magnetic semiconductors. Further, in transition‐metal compounds, d–d electronic transitions, arising from excitations between crystal‐field‐split d orbitals, significantly influence the optical and magnetic properties, particularly in strongly correlated and low‐dimensional systems. Fe 2 P 2 S6, a layered antiferromagnetic semiconductor, offers a rich platform for studying the interplay between spin, charge, and lattice degrees of freedom in these 2D systems. In this work, we investigate the photoluminescence (PL) properties of Fe 2 P 2 S 6 to probe exciton dynamics, intra‐atomic transitions, and their temperature evolution. Two prominent d–d emission peaks are observed at ∼1.63 eV (D1) and ∼1.80 eV (D2), attributed to the crystal‐field‐split Fe 2+ states. An excitonic emission near the band edge is also identified, which exhibits a characteristic Fano asymmetric line shape. This asymmetry is attributed to the quantum interference between the discrete excitonic state and the d–d transition induced continuum (D2), revealing a Fano resonance behaviour. This exciton peak disappears well before the Néel temperature, indicating its faster destabilisation than magnetic ordering. Temperature‐dependent PL measurements show a quenching of the excitonic peak with increasing temperature. Our findings provide detailed insight into the optical excitation pathways in Fe 2 P 2 S 6 .

TaSb_2, a member of the transition metal dipnictide family of materials, hosts the very rare dual topological phase - weak topological insulating state and topological crystalline insulating state along different crystallographic orientations. So far, studies on the electronic structure of transition metal dipnictides have focused on their overall electronic structure and the bulk open-orbit Fermi surfaces. Using angle-resolved photoemission spectroscopy, density functional theory calculations, and transport measurements, we distinguish the intertwined bulk and surface states on the weakly topological (201̅) plane of TaSb_2. We identify multiple electron- and hole-like bulk bands, yielding a near-perfect carrier compensation. Crucially, we observe open-orbit FSs parallel to L̅-Y̅ direction that are entirely of surface origin. Circular-dichroism ARPES reveals k → -k spectral reversal, indicating spin-momentum locking and the topological nature of these surface states. Consistent with this, magnetotransport measurements display weak antilocalization, establishing TaSb_2 as a platform for spin-polarized topological transport on a weakly topological surface.

The exactly solvable Kitaev model with its frustrated bond-dependent interactions has attracted enormous attention due to its exotic physics hosting fractional spin excitations as well as its promising prospects for quantum information technology. However, there is no pristine realization of the Kitaev model due to the significant Heisenberg and off-diagonal exchange interactions. While these additional exchange interactions are considered as obstacles on the route towards the desired Kitaev quantum spin liquids, the interplay between these magnetic anisotropies and the Kitaev interaction has lead to numerous intriguing phenomena. Here we demonstrate a new phenomenon, the coexistence of the Kitaev interaction with the piezomagnetoelectric effect (simultaneous magnetoelastic and magnetoelectric responses), which can offer electric field driven manipulation of the ground state and the fractional spin excitations. Our study reports the direct observation of the magnetoelectric (ME) effect in a Kitaev-Heisenberg, the quantum spin liquid candidate Na2Co2TeO6, and highlights the magnetoelastic response as a sensitive gauge of phase transitions. We discuss that the ME effect originates from the pd-hybridization mechanism, which allows local polarization independently from any magnetic order. This mechanism can transfer the frustrated magnetic interactions onto the polarization system, potentially creating a new exotic electronic state, a polarization liquid.

We report a transverse-field muon-spin rotation/relaxation (μSR) study of the internal-field distribution in the mixed state of LaFeAsO_0.89F_0.11 and LaFeAsO_0.75H_0.25, representative of the first (SC1) and second (SC2) superconducting domes of the LaFeAsO_1-xM_x (M= F,H) family, respectively. Below the superconducting transition temperature T_ c, the linewidth of the internal-field distribution increases in both samples, indicating the formation of a vortex lattice. Above T_ c, the linewidth remains field dependent and increases approximately linearly with field, consistent with broadening of the powder spectrum caused by an anisotropic Knight shift. After subtraction of this normal-state contribution, the superconducting linewidth σ_ sc exhibits qualitatively different field dependences in the two samples. At 4K, the SC1 (x_ F=0.11) sample shows the expected monotonic decrease with increasing field, whereas the SC2 (x_ H=0.25) sample develops a pronounced local maximum near 3T. A contour representation of σ_ sc(T,H) further reveals a ridge of local maxima whose field position, H_σ,max(T), shifts to lower fields upon warming and disappears near T_ c. The anomalous field evolution observed in the SC2 sample is consistent with an additional field-induced contribution associated with enhanced Pauli-paramagnetic effects, highlighting the distinct electronic character of the two superconducting domes.

Magnetic materials with strong spin-orbit coupling (SOC) are essential for the advancement of spin-orbitronic devices, as they enable efficient spin-charge conversion, complex magnetic structures, spin-valley physics, topological phases and other exotic phenomena. 5d transition-metal oxides such as SrIrO3 feature large SOC, but usually show paramagnetic behavior due to broad bands and a low density of states at the Fermi level, accompanied by a relatively low Coulomb repulsion. Here, we unveil ferromagnetism in 5d SrIrO3 thin films grown on SrTiO3 (111). Through substrate-induced structural engineering, a zigzag stacking of three-unit-cell thick layers along the [111] direction is achieved, stabilizing a ferromagnetic state at the interfaces. Magnetotransport measurements reveal an anomalous Hall effect below similar to 30 K and hysteresis in the Hall conductivity below 7 K, indicating ferromagnetic ordering. X-ray magnetic circular dichroism further supports these results. Theoretical analysis suggests that the structural engineering of the IrO6 octahedral network enhances the density of states at the Fermi level and thus stabilizes Stoner ferromagnetism. This work highlights the potential of structurally engineered 5d oxides for spin-orbitronic devices, where efficient control of SOC-induced magnetic phases by electric currents can lead to lower energy consumption and improved performance in next-generation device technologies.

We present a comprehensive temperature-dependent inelastic light scattering (Raman) study on single crystals of two-dimensional CuCrP2S6, a layered van der Waals material exhibiting coupled magnetic and electric degrees of freedom. Raman measurements were performed from 5 to 300 K to probe the phonon dynamics across multiple structural and magnetic phase transitions. Our analysis reveals pronounced thermal hysteresis in phonon frequency, line width, intensity and dynamic Raman susceptibility, confirming the first-order nature of the antipolar transition near T C1 similar to 145 K and a second-order transition near T C2 similar to 190 K. Low-frequency modes associated with Cu+ and Cr3 + ions exhibit softening and anomalous line width behavior, in particular phonon mode P2 (similar to 37 cm-1), which shows nonmonotonic temperature dependence and intensity enhancement near 60 K, suggesting persistent off-center Cu+ dynamics in the quasi-antipolar phase. The coexistence and coupling of soft phonon modes and central peaks indicate a crossover from displacive to order-disorder type transition mechanisms. Additionally, phonon anomalies below the Neel temperature (T N similar to 32 K) reflect spin-phonon coupling, linking lattice vibrations to long-range magnetic correlations. Our findings provide critical insight into the lattice instabilities, symmetry evolution, and quasiparticle interactions in CuCrP2S6, offering a deeper understanding of phase transition dynamics in two-dimensional multiferroic systems and guiding the future design of magnetoelectric and spintronic devices.

Two-dimensional (2D) TaS2 has emerged as a compelling platform for investigating collective electronic phenomena, particularly due to its intricate charge density wave (CDW) phases. To probe nanoscale CDW behavior and superconductivity, the synthesis of high-quality 1T-TaS2 nanocrystals (NCs) is required. In this work, we report for the first time the optimized synthesis of highly crystalline 1T-TaS2 NCs via a thermodynamically optimized chemical vapor transport approach. A comprehensive investigation was conducted to evaluate the influence of key growth parameters, including substrate type (SiO2/Si, c-sapphire, and mica), substrate temperature, growth duration, and transport agent concentration on the resulting crystal morphology and lateral dimensions. Various techniques have been employed to characterize the produced NCs including optical microscopy (OM), atomic force microscopy (AFM), scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy (SEM-EDX), Raman spectroscopy, and high-resolution transmission electron microscopy (HRTEM). Our findings highlight the critical role of the substrate in the growth dynamics and provide a versatile platform for controlled synthesis of the 1T-TaS2 phase, paving the way for its integration into next-generation electronic and quantum technologies.

We report a rich anisotropic magnetic phase diagram of Na3Co2SbO6, a previously proposed cobaltate Kitaev candidate, based on field- and temperature-dependent magnetization, specific heat, and magnetocaloric effect studies. At low temperatures, our experiments uncover a low-lying jeff = 12 state with an antiferromagnetic (AFM) ground state and pronounced in-plane versus out-of-plane anisotropy. The experimentally identified magnetic phases are theoretically characterized through classical Monte Carlo simulations within an extended Kitaev-Heisenberg model with additional ring exchange interactions. The resulting phase diagram reveals a variety of exotic field-induced magnetic phases, including double-q, 31 -AFM, zigzag, and vortex phases.

AgCrP2S6 serves as a versatile system to probe dynamics of the quasiparticle excitations as well as multiple phase transitions with lowering temperature linked with the polar, lattice and spin degrees of freedom. Here, we report in-depth temperature- and polarization-dependent Raman scattering measurements on single crystals of quasi-2D zigzag antiferromagnetic AgCrP2S6, along with first principles-based phonon calculations. We observed multiple phase transitions triggered by the short- and long-range ordering of spins at similar to 90 K and 20 K, respectively, within the Cr sublattice, where spins are arranged in a 1D chain, as evident from the distinct anomalies in the phonon-mode self-energy parameters and intensity. Contrary to the conventional belief, we proposed the possibility of quasi-antipolar ordering at similar to 200 K and with further lowering in temperature an antipolar ordering at similar to 140 K attributed to the Ag ions, which is conjectured to be forbidden owing to the heaviness of Ag ions. The quasi-antipolar and antipolar orderings are gauged via a distinct renormalization of the parameters of phonons, which exist at all the temperatures. Additionally, a large number of modes appeared with the decrease in temperature, in the range of similar to 200-140 K, where antipolar ordering started settling in. The emergence of a large number of phonon modes below similar to 200 K, nearly double that at room temperature, suggests the lowering of symmetry from high-temperature C2h to low-temperature C2 or Cs.

Magnetic topological insulators can host chiral 1D edge channels at zero magnetic field, when a magnetic gap opens at the Dirac point in the band structure of 2D topological surface states, lead- ing to the quantum anomalous Hall effect in ultra-thin nanostructures. For thicker nanostructures, quantization is severely reduced by the co-existence of edge states with other quasi-particles, usually considered as bulk states. Yet, surface states also exist above the magnetic gap, but it remains difficult to identify electronic subbands by electrical measurements due to strong disorder. Here we unveil surface states in MnBi2Te4 nanostructures, using magneto-transport in very-high magnetic fields up to 55 T, giving evidence of Shubnikov-de-Haas oscillations above 40 T. A detailed analysis confirms the 2D nature of these quantum oscillations, thus establishing an alternative method to photoemission spectroscopy for the study of topological surface states in magnetic topological insulators, using Landau level spectroscopy.

Chromium antimonide has emerged as a key material platform for studying altermagnetism because of its simple binary composition, high Néel temperature, and semimetallic electronic structure. Here, we investigate electrical and thermal magnetotransport in single-crystalline CrSb using steady-and pulsed-magnetic fields up to 65 T, and complement these measurements with neutron diffraction and magnetization data. We confirm the compensated magnetic structure and observe a large nonsaturating magnetoresistance together with a pronounced nonlinear Hall response at low temperatures. Multicarrier modeling, supported by mobility-spectrum analysis, reveals coexisting electron- and hole-like charge carriers with mobilities up to 3000 cm2/Vs and shows that the number of transport channels that can be resolved strongly depends on the accessible magnetic-field range. Thermal-transport measurements further reveal a nonlinear thermal Hall response and a thermal conductivity substantially exceeding a simple Wiedemann-Franz law. The broadly similar field and temperature evolution of electrical and thermal transport point to a dominant electronic contribution, while the remaining deviations indicate additional heat-carrying channels.

Multi-terminal topological devices are a new generation of electronic devices with quantized properties robust against imperfections. In magnetic topological insulators, dissipationless 1D chiral edge states give functional devices in zero magnetic field, of interest for quantum metrology or topological electronics. Here, we show that simple quantum circuits (disk and rings) with non-Hermitian topology, based on the interconnection of Chern states in the quantum anomalous Hall regime, can have a much stronger quantization of their invariant than that of the Chern invariant itself, when measured in a non-metrology grade setup, that is, in industry-relevant conditions. Remarkably, the chirality-related non-Hermitian skin effect shows a record degree of localization for a quantum Hall device. This new type of topological quantum device based on magnets can operate at liquid-helium temperature with a good quantization and have some potential as cryogenic sensors for applications in high-precision impedance or magnetic field measurements.

Intercalation of spin-bearing 3d transition metals into nonmagnetic transition metal dichalcogenides (TMDs) offers an effective route to induce and control magnetism in layered materials. However, progress has been hindered by the lack of scalable and controllable synthesis methods, which are mainly based on chemical vapor transport and subsequent mechanical exfoliation. Here, we utilize a scalable atmospheric pressure chemical vapor deposition (APCVD) approach to intercalate Cr into the van der Waals (vdW) gaps of 2H-NbS2. Energy-dispersive X-ray spectroscopy shows that the produced hexagonal crystals closely match the Cr1/3NbS2 stoichiometry, a chiral helimagnet of interest for spintronic applications. Transmission electron microscopy and Raman spectroscopy further verify the successful preparation of Cr1/3NbS2 with a dominantly ordered 3 & times; 3 Cr superlattice. Linear/circular polarized Raman measurements together with density functional theory calculations were utilized to assign vibrational mode symmetries in Cr1/3NbS2, serving as clear guidelines for future studies. Magneto-transport measurements revealed a strong dependence of the magnetic properties of Cr1/3NbS2 on the thickness. Interestingly, crystals thinner than the helix pitch deviate from the conventional in-plane helical structure, which gives rise to an out-of-plane magnetic component under an applied perpendicular magnetic field. This work introduces a scalable route for synthesizing magnetic intercalated TMDs and provides a platform for exploring the thickness-property relationships in low-dimensional chiral helimagnets.

We investigated the lattice dynamics of the unconventional superconductor LiFeAs using inelastic neutron scattering experiments and density-functional theory (DFT) calculations. By comparing the neutron scattering intensities with lattice-dynamics simulations we can identify the polarization symmetry of all modes along the main-symmetry directions yielding a complete experimental picture of the phonon dispersion. Overall there is good agreement between the experimental and DFT results, which renders an overlooked strong electron phonon coupling unlikely. Our DFT calculations reveal only a small averaged electron-phonon coupling constant. The transversal acoustic in-plane branches exhibit a normal dispersion for small propagation vectors indicating the absence of a nematic instability. Several modes exhibit considerable hardening upon cooling that can be attributed to the anisotropic shrinking of the LiFeAs lattice.

Delafossite compounds containing rare-earth ions have been proven to be an ideal platform to investigate frustrated magnetic ground states. Here, we discuss two triangular-lattice antiferromagnets, TlErSe_2 and TlTmSe_2, as potential candidates for hosting exotic quantum states. Powder X-ray diffraction data analysis of the black-color polycrystalline TlRESe_2 (RE: Er and Tm) samples confirms the phase purity. Both materials crystallize in the trigonal α-NaFeO_2 structure (R3m) with lattice parameters a = 4.1070(4) Å and c = 23.1472(1) Å for the erbium compound and a = 4.0916(1) Å and c = 23.1483(2) Å for the thulium compound. Magnetic susceptibility measurements show an effective moment of μ_eff = 9.6(2) μ_B/f.u. (7.5(1) μ_B/f.u.) for TlErSe_2 (TlTmSe_2) for temperatures above 200 K. While ^3He specific-heat measurements reveal long-range magnetic order below T_N = 0.42K for TlErSe_2, no sign of long-range magnetic order was observed for TlTmSe_2. Based on our results, we map out the T-H phase diagram for polycrystalline TlErSe_2 and discuss the striking difference in the magnetic behavior of TlTmSe_2 based on our ab initio quantum chemical calculations.

We study the phonon behavior of the Co-based honeycomb frustrated magnet Na2Co2TeO6 under a magnetic field applied perpendicular to the honeycomb plane. The temperature and field dependence of the sound velocity and sound attenuation unveil prominent spin-lattice coupling in this material, promoting ultrasound as a sensitive probe for magnetic properties. An out-of-plane ferrimagnetic order is determined below the N & eacute;el temperature TN = 27 K. A comprehensive analysis of our data further supports a triple-Q ground state of Na2Co2TeO6. Furthermore, the ultrasound data were systematically compared to the thermal transport results from literature, to unveil the importance of the phononic contribution to the observed transport behaviors.

Applying angle-resolved photoemission spectroscopy and density functional theory calculations, we present compelling spectroscopic evidence demonstrating the intertwining and mutual interaction between the Kondo and kagome sublattices in heavy-fermion intermetallic compound YbV_6Sn_6. We reveal the Yb 4f-derived states near the Fermi level, along with the presence of bulk kagome bands and topological surface states. We unveil strong interactions between the 4f and itinerant electrons, where the kagome bands hosting the Dirac fermions and van Hove singularities predominate. Such findings are well described using a c-f hybridization model. On the other hand, our systematic characterization of magnetic properties demonstrates an unusually enhanced antiferromagnetic ordering, where the kagome-derived van Hove singularities near E_F play a vital role in determining the unconventional nature of the Ruderman-Kittel-Kasuya-Yosida interaction and Kondo coupling. These unique kagome-state-mediated exchange interactions have never been reported before and could lead to a novel phase diagram and various quantum critical behaviors in YbV_6Sn_6 and its siblings. Our results not only expand the family of exotic quantum phases entangled with kagome structure to the strongly correlated regime, but also establish YbV_6Sn_6 as an unprecedented platform to explore unconventional many-body physics beyond the standard Kondo picture.