Ising ferromagnetic kagome metal TbV₆Sn₆

The synthesis and characterization of the vanadium-based kagome metal TbV₆Sn₆ is presented. A signature of a phase transition at 4.1K is observed in heat capacity, resistivity, and magnetic susceptibility measurements, and both resistivity and magnetization measurements exhibit hysteresis in c-axis magnetic field. Furthermore, a strikingly large anisotropy in the magnetic susceptibility is observed, with the c-axis susceptibility nearly 100 times the ab plane susceptibility at 2K. This is highly suggestive of uniaxial ferromagnetism, and the large size of 9.4μ_B/f.u. indicates the Tb³⁺ 4f electronic moments cooperatively align perpendicular to the Sn kagome lattice plane. The entropy at the phase transition is nearly Rln(2), indicating that the CEF ground state of the Tb³⁺ ion is a doublet, and therefore TbV₆Sn₆ presents an ideal system to study the interplay between Ising ferromagnetism and non-trivial electronic states emerging from a kagome lattice.