Magnetic properties of the layered heavy-fermion antiferromagnet CePdGa6

We report the magnetic properties of the layered heavy-fermion antiferromagnet CePdGa6 and their evolution upon tuning with the application of magnetic field and pressure. CePdGa6 orders antiferromagnetically below TN = 5.2 K, where there is evidence for heavy-fermion behavior from an enhanced Sommerfeld coefficient. Our results are best explained by a magnetic ground state of ferromagnetically coupled layers of Ce 4 f moments orientated along the c axis, with antiferromagnetic coupling between layers. At low temperatures, we observe two metamagnetic transitions for fields applied along the c axis corresponding to spin-flip transitions, where the lower transition is to a different magnetic phase with a magnetization one-third of the saturated value. From our analysis of the magnetic susceptibility, we propose a crystalline electric field level scheme which accounts for the Ising anisotropy at low temperatures, and we find that the evolution of the magnetic ground state can be explained considering both antiferromagnetic exchange between nearest neighbor and next-nearest neighbor layers, indicating the influence of long-range interactions. Meanwhile, we find little change of TN upon applying hydrostatic pressures up to 2.2 GPa, suggesting that significantly higher pressures are required to examine for possible quantum critical behaviors.