We have recently focused on the magnetic semiconductor YbCuS2, which has a zigzag chain of ytterbium (Yb) ions, to explore the effects of magnetic frustration. Previous nuclear quadrupole resonance (NQR) measurements revealed that YbCuS2 exhibits an incommensurate antiferromagnetic state with an ordered moment size smaller than the expected value below approximately 1 K. In addition, the presence of charge-neutral quasiparticles was observed in the magnetic ordered states. To further investigate the origin of this novel ordered state and quasiparticle excitations, experiments probing the effects of element substitutions are essential.
In this study, we performed NQR measurements on Yb0.9Lu0.1CuS2, in which Yb was partially substituted with nonmagnetic lutetium (Lu), and YbCu(S0.9Se0.1)2, in which sulfur (S) was partially substituted with selenium (Se). These substitutions correspond to magnetic dilution of the Yb sites and lattice expansion (negative chemical pressure), respectively. We revealed that both types of substitution suppress the magnetic transition temperature. Moreover, the charge-neutral quasiparticle excitations persist even after substitution. Interestingly, these substitution-induced changes exhibit a trend opposite to that observed under pressure. Our systematic study indicates a clear relationship between the magnetic ordered states and the quasiparticle excitations in YbCuS2.
The results of this study have been published in the Physical Review B.
Reference
Lu/Se substitution effect on magnetic properties of the Yb-based zigzag-chain semiconductor YbCuS2 Journal Article
In: Physical Review B, vol. 112, pp. 064414, 2025.
