A site-selective ${}^{27}\mathrm{Al}$ nuclear magnetic resonance (NMR) study is carried out on the Kondo lattice compound ${\mathrm{CePtAl}}_4{\mathrm{Ge}}_2$, which crystallizes in a rhombohedral lattice with quasi-two-dimensional Ce layers forming a triangular lattice network. Two inequivalent Al sites, Al(1) and Al(2), are unambiguously assigned by comparing measured nuclear quadrupole parameters with electric field gradients obtained from electronic structure calculations. Knight shift analysis yields distinct hyperfine coupling constants, revealing that they arise predominantly from Ruderman-Kittel-Kasuya-Yosida (RKKY)-type transferred hyperfine fields through conduction electrons. Spin-lattice relaxation measurements reveal pronounced anisotropic spin fluctuations, and a comparison of the relaxation rates between the two Al sites clarifies the momentum-space structure of these fluctuations. At low magnetic fields, ${\left(T_{1}T\right)}^{-1}$ is strongly enhanced on cooling toward the Néel temperature, indicating the growth of in-plane antiferromagnetic correlations in the paramagnetic state.

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• Magnetic anisotropy
• Spin dynamics
• Heavy-fermion systems
• Nuclear magnetic resonance