Intricate Magnetic Landscape in Antiferromagnetic Kagome Metal TbTi₃Bi₄ and Interplay with Ln_2–<i>x</i>Ti_6+<i>x</i>Bi₉ (Ln: Tb···Lu) Shurikagome Metals

Here we present the discovery and characterization of the kagome metal TbTi3Bi4 in tandem with a new series of compounds, the Ln2–xTi6+xBi9 (Ln: Tb–Lu) shurikagome metals. We previously reported on the growth of the LnTi3Bi4 (Ln: La–Gd3+, Eu2+, Yb2+) family, a chemically diverse and exfoliable series of kagome metals with complex and highly anisotropic magnetism. However, unlike the La–Gd analogs, TbTi3Bi4 cannot be synthesized by our previous methodology due to phase competition with crystals of Ln2–xTi6+xBi9 (x ∼ 1.7–1.2). Here we discuss the phase competition between the LnTi3Bi4 and Ln2–xTi6+xBi9 families, helping to frame the difficulty in synthesizing LnTi3Bi4 compounds with small Ln species and providing a strategy to circumvent the formation of Ln2–xTi6+xBi9. Detailed characterization of the magnetic and electronic transport properties on single crystals of TbTi3Bi4 reveals a highly complex landscape of magnetic phases arising from an antiferromagnetic ground state. A series of metamagnetic transitions creates at least 5 unique magnetic phase pockets, including a 1/3 and 2/3 magnetization plateau. Further, the system exhibits an intimate connection between the magnetism and magnetotransport, exhibiting sharp switching from positive (+40%) to negative magnetoresistance (−50%). Like the LnTi3Bi4 kagome metals, the Ln2–xTi6+xBi9 family exhibits quasi-2D networks of titanium and chains of rare earth. We present the structures and some basic magnetic properties of the Ln2–xTi6+xBi9 family alongside our characterization of the newly discovered TbTi3Bi4.