Nuclear quadrupole resonance (NQR) measurements were performed on the heavy-fermion superconductor Ce 3 PtIn 11 with T c = 0.32 K. The temperature dependence of both spin-lattice relaxation rate 1/T 1 and NQR spectra evidences the occurrence of two successive magnetic transitions with T N1 2.2 K and T N2 2.0 K. In successive magnetic transitions, even though the magnetic moment at the Ce(2) site plays a major role, the magnetic moment at the Ce(1) site also contributes to some extent. While a commensurate antiferromagnetic ordered state appears for T N2 < T < T N1 , a partially incommensurate antiferromagnetic ordered state is suggested for T < T N2 .

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