Magnetic structure and crystalline electric field effects in the triangular antiferromagnet CePtA l4Ge₂

Kondo metal CePtAl4Ge2 exhibits long-range antiferromagnetic order below 2.3 K. Neutron powder-diffraction experiments reveal that Ce moments order antiferromagnetically with an incommensurate ordering wave vector k=(1.39,0,0.09). Inelastic neutron powder scattering experiments show a magnetic excitation at 14.5 meV, which corresponds to the first excited state due to the crystalline electric field splitting of the ground-state multiplet of Ce³⁺. The temperature and field dependence of the magnetization of CePtAl4Ge₂ is consistent with a doublet ground state with a dominant |jz=1/2) character and a first excited doublet |jz=3/2) at 14.5 meV.