Search Results for « Kagome metals »

Abstract Recent studies on quantum materials where transition‐metal atoms give rise to ‐bands typical of kagome metals are reviewed. Using examples from several material families – , FeGe, , and – it is argued that ‐bands contributed by elements beyond the kagome network play a crucial role in the electronic instabilities, including the charge‐density waves and superconductivity in kagome metals.

Cellular lattice structures have important applications in aerospace, automobile and defense industries due to their high specific strength, modulus and energy absorption. Additive manufacturing provides the design freedom to fabricate complex cellular structures. This study investigates the compressive properties and deformation behavior of a Ti-6Al-4V unit Kagome structure fabricated by selective laser melting. Further, the mechanical performance of multi-unit and multi-layer Kagome structure of acrylonitrile butadiene styrene (ABS) ABS-M30™ manufactured by fused deposition modeling is explored. The effect of a number of layers of Kagome structure on the compressive properties is investigated. This paper also explores the mechanical properties of functionally graded and uniform density Kagome structure. The stiffness of the structure decreased with the increase in the number of layers whereas no change in peak load was observed. The functionally graded Kagome structure provided 35% more energy absorption than the uniform density structure.

Abstract Recent experiments on the kagome metal CsV 3 Sb 5 reveal a curious phase transition-like feature: a nematic magnetic torque response that abruptly sets in at T τ ≈ 130 K, above the known charge density wave transition at T CDW ≈ 100 K. Counterintuitively, elastoresistance measurements—a standard probe of nematicity—show no corresponding signal, ruling out a nematic phase transition and placing strong constraints on possible explanations. Beyond nematicity, the torque is paramagnetic for in-plane magnetic field, while above a critical out-of-plane field, an in-plane magnetisation appears, accompanied by hysteresis. We show that this combination of features cannot be accounted for by charge density waves or intraband magnetic order. Instead, we propose that interband ordering—via a symmetry-allowed interband spin-orbit coupling and a time-reversal and spatial symmetry-breaking interband order parameter—together with a background strain field, consistent with typical experimental conditions, provides a natural explanation; in our picture, the behaviour at T τ is understood as a crossover in the symmetry-allowed interband spin-orbit coupling strength. Our theory accounts for the nematic magnetic torque, hysteresis, and the transition-like onset at T τ , while also making testable predictions, including strain-induced magnetisation. In doing so, it challenges the prevailing view of the normal state.

Abstract Charge density wave (CDW) is a spontaneous spatial modulation of charges in solids whose general microscopic descriptions are yet to be completed. Kagome metals of A V 3 Sb 5 ( A = K, Rb, Cs) provide a chance to realize CDW intertwined with dimensional effects as well as their special lattice. Here, based on a state-of-the-art molecular dynamics simulation, we propose that their phase transition to CDW is a condensation process of incoherently preformed charge orders. Owing to unavoidable degeneracy in stacking charge orders, phases of preformed orders on each layer are shown to fluctuate between a limited number of states with quite slower frequencies than typical phonon vibrations until reaching their freezing temperature. As the size of interfacial alkali atom increases, the fluctuations are shown to counterbalance the condensation of orderings, resulting in a maximized transition temperature for RbV 3 Sb 5 . Our results resolve controversial observations on their CDWs, highlighting a crucial role of their interlayer interactions.

Abstract Recently, layered kagome metals A V 3 Sb 5 ( A = K, Rb, and Cs) have emerged as a fertile platform for exploring frustrated geometry, correlations, and topology. Here, using first-principles and mean-field calculations, we demonstrate that A V 3 Sb 5 can crystallize in a mono-layered form, revealing a range of properties that render the system unique. Most importantly, the two-dimensional monolayer preserves intrinsically different symmetries from the three-dimensional layered bulk, enforced by stoichiometry. Consequently, the van Hove singularities, logarithmic divergences of the electronic density of states, are enriched, leading to a variety of competing instabilities such as doublets of charge density waves and s - and d -wave superconductivity. We show that the competition between orders can be fine-tuned in the monolayer via electron-filling of the van Hove singularities. Thus, our results suggest the monolayer kagome metal A V 3 Sb 5 as a promising platform for designer quantum phases.

The connectivity and inherent frustration of the kagome lattice can produce interesting electronic structures and behaviors in compounds containing this structural motif. Here we report the properties of Pt3X2 (X = In and Tl) that adopt a double-layer kagome net structure related to that of the topologically nontrivial high-temperature ferromagnet Fe3Sn2 and the density wave hosting compound V3Sb2. We examined the structural and physical properties of single crystal Pt3Tl2 and polycrystalline Pt3In2 using X-ray and neutron diffraction, magnetic susceptibility, heat capacity, and electrical transport measurements, along with density functional theory calculations of the electronic structure. Our calculations show that Fermi levels lie in pseudogaps in the densities of states with several bands contributing to transport, and this is consistent with our Hall effect, magnetic susceptibility, and heat capacity measurements. Although electronic dispersions, characteristic of simple kagome nets with nearest-neighbor hopping, are not clearly seen, likely due to the extended nature of the Pt 5d states, we do observe moderately large and non-saturating magnetoresistance values and quantum oscillations in the magnetoresistance and magnetization associated with the kagome nets of Pt.