Spin-Density-Wave-Type Ordering of LaCoGe Revealed by ^{59}Co- and ^{139}La-Nuclear Magnetic Resonance Measurements

TL;DR

This study reveals that LaCoGe exhibits spin-density-wave-type antiferromagnetic ordering below 18 K, characterized by inhomogeneous magnetic moments aligned along the c-axis, as evidenced by ^{59}Co- and ^{139}La-NMR measurements.

Contribution

First demonstration of SDW-type magnetic ordering in LaCoGe using NMR techniques, highlighting inhomogeneous magnetic moments and anisotropic magnetic correlations.

Findings

Antiferromagnetic ordering below 18 K.

Inhomogeneous internal magnetic field at Co sites.

Checkerboard magnetic correlations in the ab-plane.

Abstract

The low-temperature magnetic properties of LaCoGe with the tetragonal CeFeSi-type structure were investigated by ^{59}Co- and ^{139}La-nuclear magnetic resonance (NMR) and nuclear quadrupole resonance (NQR) measurements. The nuclear spin-lattice relaxation rate divided by the temperature, 1/(T_1 T), gradually increases with decreasing temperature and shows a kink at approximately 18 K, below which an inhomogeneous internal field appears at the Co nuclear site. These results indicate that antiferromagnetic ordering occurs below T_N ~ 18 K. However, an internal field was not observed at the La nuclear site below T_N. Taking all NMR results into account, we conclude that spin-density-wave (SDW)-type ordering occurs, where magnetic correlations are of the checkerboard type in the ab-plane and have a long periodicity along the c-axis with inhomogeneous ordered moments pointing to the c-axis.