We report a unified, tool-driven approach for the rational design and synthesis leading to the growth of hybrid Yb 3 Rh 4 Sn 13 /LaRuSn 3 .

The kagome RMn_6Sn_6 material family has attracted significant attention as high-temperature metallic magnets with a host of different magnetic orderings and anisotropy. Theoretical studies point to the rare-earth (R) as the determining factor for both the direction of magnetic anisotropy and the type of magnetic ordering in a given compound. This motivates studying high-entropy forms of RMn_6Sn_6 to examine how the interplay of several rare-earth elements leads to different magnetic states in a single crystal. Here, we present a rare-earth mix of Tb, Dy, Ho, Er, Tm, and Lu that produces phase transitions from a paramagnet to an easy-plane ferrimagnet (FiM) below T_C = 380 K, then to a FiM easy-axis state at T_SR1 = 207 K, to a canted FiM ground state below T_SR2 = 79 K. This behavior is consistent with previously reported high-entropy RMn_6Sn_6 compounds; however, uniquely, the rare-earth mix studied here exhibits a broad transition from easy-plane to easy-axis anisotropy from 270 K to 170 K, and reveals a nonmonotonic magnetoresistance. Using neutron scattering data, we found that both observations correlate with an incommensurate modulated contribution to the spin state due to competing rare-earth interactions. This magnetoresistive behavior and the correlated spin structures underscore the potential for rare-earth engineering of magnetism.

Fe3GaTe2 is a van der Waals (vdW) ferromagnet with a Curie temperature TC ranging from 350 to 380 K, followed upon cooling by a ferrimagnetic transition near room temperature. Substituting Fe with Co was previously reported to induce antiferromagnetism (AFM) at a Co fraction-dependent Néel temperature TN. In this work, we confirm the overall phase diagram of the Fe3-xCoxGaTe2 series as a function of x and temperature via magnetization and electrical transport measurements. For x ⩾ 0.6, the Hall effect is observed to mimic the magnetization as the AF ground state is suppressed by the external magnetic field via a metamagnetic transition, thus displaying an anomalous Hall response. At low temperatures, we also observe a pronounced topological Hall signal peaking at μ0H = 4 T, or within the metamagnetic transition region of fields. This observation points to the presence of magnetic field-induced chiral spin textures, such as skyrmions, upon approaching magnetization saturation. Magnetic force microscopy (MFM) reveals the emergence of nearly circular magnetic domains, with diameters on the order of 100-200 nm, within the antiferromagnetic phase. A detailed analysis of the MFM images indicates that the topological Hall effect is closely linked to the field-induced stabilization of magnetic domain structures, likely exhibiting chiral textures. This observation suggests the possible formation of skyrmions already in the AFM phase, i.e., AFM skyrmions, that evolve into ferromagnetic (FM) ones upon increasing the magnetic field. Consequently, Co-doped Fe3GaTe2 might provide a platform to investigate the transformation of skyrmions, initially coupled antiferromagnetically into ferromagnetic ones, and to explore its impact on the topological and skyrmion Hall effects.

While polymorphism in kagome-derived intermetallics offers a powerful route to controlling structure-property relationships, it still remains poorly explored for many rare-earth members due to synthetic constraints. Here, we report the discovery and controlled growth of two previously unreported polymorphs of SmFe6Ge6 adopting an orthorhombic structure (space group Immm), realized in both ordered and disordered variants. Differential scanning calorimetry (DSC) was employed to identify critical thermal events, enabling the development of targeted flux-growth conditions that selectively stabilize each polymorph. High-quality single crystals were obtained and structurally characterized by single crystal and powder X-ray diffraction, revealing differences in Sm-site ordering within the same crystallographic framework. X-ray absorption spectroscopy confirms the Sm valence state of 3+. Anisotropic magnetic measurements performed on oriented single crystals demonstrate pronounced directional dependence of the magnetic response, while 57Fe Mössbauer spectroscopy revealed that the Fe sublattice participates in at least two field-induced metamagnetic transitions yielding phases with sizable canting of Fe moments. These results establish flux chemistry, guided by thermal analysis, as a decisive parameter for directing polymorph selection and crystallographic order in rare-earth kagome systems, expanding the accessible structural landscape of AM6X6 materials.

In the search for unconventional magnetism, exotic quantum states are characterized by a lack of order and a broad spin excitation continuum approaching zero temperature. We study the two-dimensional triangular-lattice effective spin-[Formula: see text] system CeMgAl11O19, which shows slight disorder but no magnetic ordering down to 100 millikelvin. Spin-wave analysis in the magnetic-field-polarized state determines the spin Hamiltonian featuring a mixed ferromagnetic-antiferromagnetic nearest-neighbor exchange interaction [[Formula: see text] = -0.024(5) milli-electron volts, [Formula: see text] = 0.056(3) milli-electron volts]. This places the system near an exactly solvable point of the spin-[Formula: see text] triangular-lattice XXZ model ([Formula: see text]) with extensive ground-state degeneracy. In zero field, neutron spectroscopy reveals a prominent continuum; we show that this arises from an ensemble average of spin-wave spectra across the degenerate ground-state manifold. This demonstrates that the role of weak quenched disorder can be quantitatively constrained: It inhibits unique ground-state selection and stabilizes a local distribution within the degenerate manifold, yielding continuum-like spectra that necessitate a critical reevaluation of the experimental signatures of exotic quantum states.

Single crystals of an orthorhombic polymorph of kagome metal YbFe6Ge6 were grown from Zn flux. This Zn-flux-stabilized phase exhibits mixed Yb valency and magnetic behavior that differs from its hexagonal counterpart, underscoring the profound influence of flux selection on both structure and physical properties in intermetallic materials.

In this work, we report the discovery of a new crystal structure on the Ge-rich side of the Pr-Ge binary phase diagram. Using a high-temperature flux technique, we grew single crystals of Pr_9Ge_16, which adopt a previously unreported orthorhombic Fdd2 structure type featuring ordered Ge vacancies. We present the anisotropic magnetic properties and identify the crystallographic b axis perpendicular to the crystal plane as the magnetic easy axis. Temperature-dependent resistivity measurements reveal metallic behavior with a distinct anomaly at T_C = 14.3 K. Hall resistivity data indicate that electron-like carriers dominate, with a carrier concentration on the order of 10^27 m^-3. The magnetic order is readily suppressed by a magnetic field of approximately 0.4 T applied along the easy b axis.

The large anomalous Hall conductivity (AHC) of the Fe3(Ge, Ga)Te2 compounds has attracted considerable attention. Here, we expose the intrinsic nature of the AHC in Fe3GaTe2 crystals characterized by high conductivities, which show disorder-independent AHC with a pronounced value sigma xc y approximate to 420 Q-1cm-1. In the low-conductivity regime, we observe the scaling relation Qxy oc axx1.6, which crosses over to Qxy sigma xc y as axx increases. Disorder in low-conductivity crystals is confirmed by the broadening of a first-order transition between ferromagnetism and the ferrimagnetic ground state. Through density functional theory (DFT) calculations, we reveal that the dominant sources of Berry curvature are located a few hundred meV below the Fermi energy around the P point. Therefore, Fe3GaTe2 clearly exposes the disorder-induced crossover among distinct AHC regimes, previously inferred from measurements on different ferromagnets located on either side of the crossover region.

Quantum materials that are found on the verge of structural, magnetic, and electronic instabilities are deep reservoirs for exotic phenomena. Our criteria to study the reported Ln5Ru6Sn18 (Ln = Gd, Tb) are guided by the tolerance factor for Remeika phases-a class of intermetallic compounds with the general formula A3M4X13 (where A = rare-earth element, M = transition metal, and X = tetrel), which can be viewed as structural analogues of pseudoperovskites (4 x ABX3), with one of the tetrel atoms occupying the A-site. We have grown single crystals, up to 0.5 cm on the largest facet, of Gd5Ru6Sn18 (a = 13.8052(12) angstrom) and Tb5Ru6Sn18 (a = 13.7825(9) angstrom), which we expect to be on the verge of a formation instability. Bulk magnetic, heat capacity, and electrical transport measurements reveal unusual behavior that originates from the trivalent Gd and Tb ions, with deviations from typical metallic behavior and magnetic ordering that is short-range or disrupted in some other way. To better understand these phenomena, single-crystal neutron diffraction is investigated, which reveals short-range correlations among the partially occupied Tb and Sn sublattices, with 3D-Delta PDF analysis supporting direction-dependent local order. Taken together, these measurements show the utility of using tolerance factors in identifying materials that are likely to exhibit complex phenomena and uncover environments where a formation instability may strongly impact emergent bulk magnetic and electronic phenomena.

Intergrowth phases in intermetallic systems provide a compelling framework for investigating structure-property relationships as a function of crystallographic subunit stacking. In this study, we examine the influence of Mn vacancy ordering on subunit stacking and reassign the structure of Ce2MnGe6 to a monoclinic C2/m space group (a = 8.3486(17) & Aring;, b = 8.6181(18) & Aring;, c = 10.778(2) & Aring;, beta = 101.17(2)degrees). Additionally, we report a monoclinic polymorph of the Ln2MGe6 family characterized as a tripled c-axis supercell derivative of monoclinic Ce2MnGe6, 3xc-Ce2MnGe6 (a = 8.3482(16) & Aring;, b = 8.6179(18) & Aring;, c = 31.813(6) & Aring;, beta = 93.763(7)degrees). This polymorph emerges under rapid cooling conditions during the synthesis and offers insight into the structural relationship between the orthorhombic and monoclinic variants of the Ln2MGe6 phases. Notably, the supercell form of Ce2MnGe6 (3xc-Ce2MnGe6) exhibits increased electrical resistivity and suggests enhanced Zintl-like behavior, potentially indicating greater thermodynamic stability relative to the parent monoclinic phase.

The homologous series Ln n+1M n Ge3n+1 (Ln = Ce, Pr, M = Fe, Co) has proven to be a fruitful platform for tuning physical properties as a function of subunit stacking. In this study, we investigate the crystal growth, structure, and physical properties of PrFeGe3, aiming to deconstruct Pr4Fe3Ge10 (n = 3) into its subunits, including the BaNiSn3 and CeNiSi2 structure types. The electrical resistivity and magnetic susceptibility of PrFeGe3 were measured. The magnetic properties reveal PrFeGe3 to be antiferromagnetic (5 K) with an effective moment of mu eff = 4.38 mu B/F.U., larger than the spin-only moment from Pr3+ (3.58 mu B). Due to the large magnetic moment observed, the oxidation state of the elements was determined using spectroscopic methods, including X-ray absorption spectroscopy and X-ray photoelectron spectroscopy. The neutral oxidation state of iron determined from X-ray photoelectron spectroscopy supports the itinerant magnetic behavior of iron. Annealing, in tandem with differential scanning calorimetry, revealed PrFeGe3 to be a precursor for the formation of new homologous series members.

Magnetically intercalated transition metal dichalcogenides (TMDs) provide a versatile three-dimensional (3D) material platform to explore quantum phenomena and functionalities that emerge from an intricate interplay among magnetism, band structure, and electronic correlations. Here, we report the observation of a nearly magnetization-free anomalous Hall effect (AHE) accompanied by non-Fermi liquid (NFL) behavior and collinear antiferromagnetism (AFM) in V1/3NbS2. Our single-crystal neutron diffraction measurements identify a commensurate, collinear AFM order formed by intercalated V moments. In the magnetically ordered state, the spontaneous AHE is tenfold greater than expected from empirical scaling with magnetization, and this strongly enhanced AHE arises in the NFL regime that violates the quasiparticle picture. V1/3NbS2 challenges the existing single-particle framework for understanding AHEs based on one-body Berry curvature and highlights the potential of magnetically intercalated TMDs to unveil new electronic functionalities where many-body correlations play a critical role.

The layered compound Fe3GaTe2 is attracting attention due to its high Curie temperature, low dimensionality, and the presence of topological spin textures above room temperature, making Fe3GaTe2 a good candidate for applications in spintronics. Here, we show, through transmission electron microscopy (TEM) techniques, that Fe3GaTe2 single crystals break local inversion symmetry while maintaining global inversion symmetry according to X-ray diffraction. Coupled to the observation of Néel skyrmions via Lorentz-TEM, our structural analysis provides a convincing explanation for their presence in centrosymmetric materials. Magnetization measurements as a function of the temperature display a sharp first-order thermodynamic phase-transition leading to a reduction in the magnetic moment. This implies that the ground state of Fe3GaTe2 is globally ferrimagnetic and not a glassy magnetic state composed of ferrimagnetic, and ferromagnetic domains as previously claimed. Neutron diffraction studies indicate that the ferromagnetic-to-ferrimagnetic transition upon reducing the external magnetic field might be associated with a change in the magnetic configuration/coupling between Fe1 and Fe2 moments. We observe a clear correlation between the hysteresis observed in both the skyrmion density and the magnetization of Fe3GaTe2. This indicates that its topological spin textures are affected by the development of ferrimagnetism upon cooling. Observation, via magnetic force microscopy, of magnetic bubbles at the magnetic phase boundary suggests skyrmions stabilized by the competition among magnetic phases and distinct exchange interactions. Our study provides an explanation for the observation of Néel skyrmions in centrosymmetric systems while exposing a correlation between the distinct magnetic phases of Fe3GaTe2 and its topological spin textures.

In situ experiments probing the mechanisms of flux growth synthesis above 1100 degrees C, though challenging, enable direct observation of synthetic pathways, products, and metastable phases. In this study, in situ powder X-ray diffraction of flux growth synthesis up to 1200 degrees C was employed to investigate the role of Sn flux in the synthesis of praseodymium cobalt germanides. We demonstrate that metallic fluxes, with minimal incorporation into the target compounds, significantly influence the reaction products of flux growth synthesis of intermetallic compounds. The validation of in situ experiments with bulk synthesis is also presented.

An optimized synthetic method is presented for Sm2Ru3Sn5 and investigate its physical properties and electronic structure. Sm2Ru3Sn5 is prepared by arc-melting stoichiometric ratios of the elements and is confirmed by single crystal and powder X-ray diffraction. An antiferromagnetic transition is observed at TN = 3.8 K. A modified Curie-Weiss fit to the data in the range 50-150 K yields a Curie-Weiss temperature: theta CW = -36.6 K and an effective magnetic moment: mu eff = 0.83 mu B, in agreement with a Sm3+ oxidation state. Field-dependent magnetization up to H = 7 T at 2 K shows a maximum response of 0.06 mu B, which is significantly lower than the expected Sm3+ saturation moment (0.71 mu B). Resistivity measurements indicate metallic behavior, and analysis of the magnetic entropy from the heat capacity reveals a doublet ground state due to crystal electric field splitting. The electronic structure and density of states are calculated with density function theory and further supported by the local density approximation with dynamical mean-field theory. The experimental and computational results highlight localized Sm3+ moments and suggest a possible interplay between Ruddelman-Kitel-Kasuya-Yosida and Kondo interactions, positioning Sm2Ru3Sn5 as a promising material for studying topology and complex physical phenomena.

Strongly correlated f-electron systems are known to host exotic quantum states, such as quantum criticality, complex order parameters, and unconventional superconductivity. However, the appearance of these exotic states is difficult to predict, making the study of quantum critical behavior challenging, especially in ferromagnetic materials. Herein, we report a structure-property map for Ce2M3X5 (M = transition metal; X = main group element) that aids in the targeted design of materials likely to exhibit quantum criticality. Guided by this map, we report on the synthesis of single-crystalline Ce2Ru3Ge5 and provide, for the first time, magnetic susceptibility, heat capacity, resistivity, and magnetoresistance measurements on single crystals. We observe a weak ferromagnetic-like response at 7.5 K, which is contrasted with the bulk ferromagnetic ordering that appears in polycrystalline samples. Non-Fermi liquid behavior is seen in the temperature dependent electrical resistivity and heat capacity of the single crystals, suggesting proximity to a ferromagnetic quantum critical point without chemical or physical pressure. Given the contrast with previous reports of polycrystals, these results lead us to propose that single crystalline Ce2Ru3Ge5 is intrinsically tuned into the vicinity of a ferromagnetic quantum critical point.

Kagome materials provide fruitful grounds for exploring the intersection of topology and magnetism. In this article, the single crystal growth of Yb0.5(Co1-x Fe x )3Ge3 (x = 0.00, 0.25, 0.50, 0.75, and 1.00) is reported. As Fe is substituted into the Co-containing kagome net, the structure transforms from the disordered Y0.5Co3Ge3/CoSn-type hybrid structure to the ordered HfFe6Ge6-type structure. Diffusive scattering is observed in all doped concentrations that eventually converge to a single reflection in the Fe end member, ultimately doubling the unit cell along the c-axis. Anisotropic magnetic measurements were performed to evaluate how the magnetism of the kagome lattice is influenced by Fe substitution. Magnetic interactions are primarily observed along the c-axis. Additionally, a reorientation of the magnetic easy axis is observed with increasing Fe incorporation, highlighting how the magnetism of this material can be chemically tuned. Resistivity with unusual behavior observed in the doped compositions is also reported. The rationale behind the structural evolution from disordered to ordered is discussed.

Co3Ga2Ge5 was synthesized through arc-melting stoichiometric ratios of the elements, and a Ru3Sn7-type structure was confirmed by X-ray diffraction. Because Co3Ga2Ge5 contains Ga and Ge, which have very similar ray and neutron scattering factors, any Ga/Ge crystallographic site preference cannot be determined with diffraction alone. The purpose of this study is to highlight the importance of using multiple techniques characterize otherwise structurally ambiguous intermetallic compounds. We utilize 71 Ga nuclear magnetic resonance spectroscopy and an analysis of the X-ray absorption fine structure to clarify the amount of Ga/Ge site mixing. Our combined use of X-ray diffraction and spectroscopy provides a comprehensive structural analysis Ga site mixing across the Ge crystallographic sites, enhancing the understanding of the structure and properties of Co3Ga2Ge5.