Centrosymmetric lattice with frustrated triangular planes of Gd ions: GdNiAl₄Ge₂

There is ongoing interest in magnetically frustrated metals, where the interplay between structural, charge, and spin degrees of freedom often produce novel phenomena. Motivated by this, we recently investigated the compounds LnAuAl4Ge2 (Ln = lanthanide), which feature triangular nets of Ln ions and exhibit complex magnetism in some cases (e.g., Ln = Gd and Tb) [1, 2]. Here we report results for the transition metal analog GdNiAl4Ge2 and its nonmagnetic variant LuNiAl4Ge2. Magnetic, thermodynamics and electrical transport measurements reveal that the change from Au → Ni strongly impacts the ground state magnetism. In particular, we find evidence for antiferromagnetic-like ordering in small magnetic fields, which strongly evolves with increasing field and exhibits hysteresis over a limited part of the temperature (T )-magnetic field (H) phase diagram. We will present a detailed T − H phase diagram and discuss evidence for non-trivial spin textures or glassy behavior in this compound.