Uniaxial ferromagnetism in the kagome metal TbV6Sn6

The synthesis and characterization of the vanadium-based kagome metal TbV6Sn6 is presented. X-ray measurements confirm that this material forms with the same crystal structure type as the recently investigated kagome metals GdV6Sn6 and YV6Sn6 , with space group symmetry P6/mmm. A signature of a phase transition at 4.1 K is observed in heat capacity, resistivity, and magnetic susceptibility measurements, and both resistivity and magnetization measurements exhibit hysteresis in magnetic field. Furthermore, a strikingly large anisotropy in the magnetic susceptibility was observed, with the c-axis susceptibility roughly 75 times the ab plane susceptibility at 5 K. This is highly suggestive of uniaxial ferromagnetism, and the large size of 9.4 mu b/f.u. indicates the Tb3+ 4 f electronic moments cooperatively align perpendicular to the V kagome lattice plane. The entropy at the phase transition is nearly R ln(2), indicating that the crystalline electric field ground state of the Tb3+ ion is a doublet, and therefore the sublattice of 4 f electrons in this material can be shown to map at low temperatures to the Ising model in a D6h symmetry environment. Hall measurements at temperatures from 300 to 1.7 K can be described by two-band carrier transport at temperatures below around 150 K, with a large increase in both hole and electron mobilities, similar to YV6Sn6 , and an anomalous Hall effect is seen below the ordering temperature. Angle-resolved photoemission measurements above the magnetic ordering temperature reveal typical kagome dispersions. Our study presents TbV6Sn6 as an interesting system where Ising ferromagnetism coexists with nontrivial electronic states emerging from a kagome lattice.

Automated summary

The synthesis and characterization of vanadium-based kagome metal TbV6Sn6 is presented. The material exhibits phase transition behavior and magnetic anisotropy, suggesting the presence of uniaxial ferromagnetism. The study also reveals the nontrivial electronic states emerging from the kagome lattice structure.