Search for: All records

Abstract Single crystals of U₂Mn₃Ge and U₂Fe₃Ge with a Kagome lattice structure were synthesized using a high-temperature self-flux crystal growth method. The physical properties of these crystals were characterized through measurements of resistivity, magnetism, and specific heat. U₂Fe₃Ge exhibits ferromagnetic ground state and anomalous Hall effect, and U₂Mn₃Ge demonstrates a complex magnetic structure. Both compounds exhibit large Sommerfeld coefficient, indicating coexistence of heavy Fermion behaviour with magnetism. Our results suggest that this U₂TM₃Ge (TM = Mn, Fe, Co) family is a promising platform to investigate the interplay of magnetism, Kondo physics and the Kagome lattice. 

Abstract ${\mathrm{Fe}}_{3+\delta }{\mathrm{GeTe}}_2$(FGT) has proved to be an interesting van der Waals (vdW) ferromagnetic compound with a tunable Curie temperature ( $T_{\mathrm{C}}$). However, the underlying mechanism for varying $T_{\mathrm{C}}$remains elusive. Here, we systematically investigate and compare low-temperature magnetic properties of single crystalline FGT samples that exhibit $T_{\mathrm{C}}$s ranging from 160 K to 205 K. Spin stiffness (D) and spin excitation gap (Δ) are extracted using Bloch’s theory for crystals with varying Fe content. Compared to Cr-based vdW ferromagnets, FGT compounds have higher spin stiffness values but lower spin wave excitation gaps. We discuss the implication of these relationships in Fe–Fe ion magnetic interactions in FGT unit cells. The itinerancy of magnetic electrons is measured and discussed under the Rhodes–Wohlfarth ratio (RWR) and the Takahashi theory. 

Abstract Since the initial discovery of 2D van der Waals (vdW) materials, significant effort has been made to incorporate the three properties of magnetism, band structure topology, and strong electron correlations—to leverage emergent quantum phenomena and expand their potential applications. However, the discovery of a single vdW material that intrinsically hosts all three ingredients has remained an outstanding challenge. Here, the discovery of a Kondo‐interacting topological antiferromagnet is reported in the vdW 5felectron system UOTe. It has a high antiferromagnetic (AFM) transition temperature of 150 K, with a unique AFM configuration that breaks the combined parity and time reversal (PT) symmetry in an even number of layers while maintaining zero net magnetic moment. This angle‐resolved photoemission spectroscopy (ARPES) measurements reveal Dirac bands near the Fermi level, which combined with the theoretical calculations demonstrate UOTe as an AFM Dirac semimetal. Within the AFM order, the presence of the Kondo interaction is observed, as evidenced by the emergence of a 5fflat band near the Fermi level below 100 K and hybridization between the Kondo band and the Dirac band. The density functional theory calculations in its bilayer form predict UOTe as a rare example of a fully‐compensated AFM Chern insulator.