The magnetic state of the noncentrosymmetric antiferromagnet ${\mathrm{CeNiC}}_2$ has been studied by magnetic susceptibility, heat capacity, muon spin relaxation $\left(\mu \mathrm{SR}\right)$, and inelastic neutron scattering (INS) measurements. ${\mathrm{CeNiC}}_2$ exhibits three magnetic phase transitions at $T_{N_1}=19.5$ K, $T_{N_2}=10$ K, and $T_{N_3}=2.5$ K. The presence of long-range magnetic order below 20 K is confirmed by the observation of oscillations in the $\mu \mathrm{SR}$ spectra between 10 and 20 K and a sharp increase in the muon depolarization rate. INS studies reveal two well-defined crystal electric field (CEF) excitations around 8 and 30 meV. INS data have been analyzed using a CEF model and the wave functions were evaluated. We also calculated the direction and magnitude of the ground state moment using CEF wave functions and compare the results with that proposed from the neutron diffraction. Our CEF model correctly predicts that the moments order along the $b$ axis (or $y$ axis) and the estimated magnetic moment is $\mathrm{0.687(5)}{\mu }_B$, which is higher than the moment observed from the neutron diffraction $(0.25{\mu }_B/\mathrm{Ce})$. We attribute the observed reduced moment due to the Kondo screening effect.

• Received 6 March 2014
• Revised 24 July 2014

DOI:https://doi.org/10.1103/PhysRevB.90.054405