A magnetic semiconductor YbCuS2 has Yb zigzag chains, where the magnetic frustration is expected due to the competition between the nearest-neighbor exchange and next-nearest-neighbor exchange interactions. From the nuclear quadrupole resonance (NQR) measurements, we revealed that the system exhibits an incommensurate antiferromagnetic state with an ordered moment size smaller than the expected value below approximately 1 K. The emergence of charge-neutral quasiparticles was observed in the magnetic ordered states. In addition, magnetic-field-induced phase transitions in the magnetic ordered state were reported as shown in Fig. (a). These phenomena cannot be explained by conventional antiferromagnets.
In this study, we have performed the nuclear magnetic resonance (NMR) measurements to investigate the paramagnetic properties of YbCuS2 under magnetic fields. As shown in Fig. (b), a broad maximum of the nuclear spin-lattice relaxation rate 1/T1 was observed at around 50 K, and this anomaly is strongly suppressed by the magnetic field. Moreover, we observed an enhancement of 1/T1 at low temperatures above 3 T. These results suggest that the magnetic-field-induced modification occurs even in the paramagnetic state.
The results of this study have been published in the Journal of the Physical Society of Japan.
Magnetic-Field Dependence of Paramagnetic Properties Investigated by 63/65Cu-NMR on the Yb Zigzag-Chain Semiconductor YbCuS2 Journal Article
In: Journal of the Physical Society of Japan, vol. 94, pp. 024706, 2025.
