Complex magnetism in novel intermetallic compound UAgBi₂

In this work, we report the structural and physical properties of the newly synthesized UAgBi₂ intermetallic compound. UAgBi₂ crystallizes in a tetragonal HfCuSi₂-type structure (space group P4/nmm), which presents a stacking arrangement of UBi-Ag-UBi-Bi layers. Magnetic susceptibility (c) and magnetization measurements show clear evidence for a complex magnetic structure and multiple competing exchange interactions that give rise to a cascade of field-induced transitions. Curie-Weiss (CW) fits to c(T) provide an effective magnetic moment of μ_eff = 3.4 µ_B/U with an antiferromagnetic CW temperature θ_CW = -2.5 K for magnetic fields applied along the c axis (magnetic easy axis), and a ferromagnetic θ_{CW =} 75 K when the magnetic field is applied parallel to the ab plane. Two antiferromagnetic-like anomalies are observed in c(T) at T_N1 = 68 K and T_N2 = 65 K only when the magnetic field is applied parallel to the c axis. In addition, a hysteretic anomaly is observed around T_M3 = 25 K for both directions of the applied magnetic field. We will discuss specific heat, electrical resistivity, Hall effect, and thermal expansion measurements in light of crystalline electrical field effects and competing magnetic interactions to understand the intricate magnetic ground state of UAgBi₂.

Email for the corresponding author:

gfreitas@lanl.gov