Static and Dynamic Electronic Properties and the Possible Magnetic Structure of the $4f^3$-$\Gamma_6$ System NdCo2Zn$_{18}$Ga$_2$ Investigated Using $^{59}$Co Nuclear Quadrupole Resonance

Abstract

We report $^{59}$Co nuclear quadrupole resonance (NQR) measurements on the Nd-based compound NdCo$_2$Zn$_{18}$Ga$_2$, which undergoes an antiferromagnetic transition at $T_{\rm N} = 1.5$ K. Although the NQR spectra show no detectable change across $T_{\rm N}$, the nuclear spin-lattice relaxation rate, $1/T_1$, exhibits a clear anomaly at $T_{\rm N}$. An analysis based on the alignment of the Nd moments demonstrates that the internal magnetic fields generated by these moments cancel each other at the Co sites. If the nearest-neighbor Nd moments align antiferromagnetically, this finding suggests that Ga substitution removes magnetic frustration, thereby increasing $T_{\rm N}$.