Junghyun Kim1,2,Jonghyeon Kim3,Woongki Na4,Pyeongjae Park1,2,Hyeonsik Cheong4,Jae Hoon Kim3,Je-Geun Park1,2
Center for Quantum Materials, Seoul National University1,Department of Physics & Astronomy, Seoul National University2,Department of Physics, Yonsei University3,Department of Physics, Sogang University4
Junghyun Kim1,2,Jonghyeon Kim3,Woongki Na4,Pyeongjae Park1,2,Hyeonsik Cheong4,Jae Hoon Kim3,Je-Geun Park1,2
Center for Quantum Materials, Seoul National University1,Department of Physics & Astronomy, Seoul National University2,Department of Physics, Yonsei University3,Department of Physics, Sogang University4
The antiferromagnetic van der Waals (vdW) NiPS<sub>3</sub> is a rare material for studying the exciton physics based on the magnetically ordered system. The extremely narrow linewidth of the exciton peak arising coherently from the Zhang-Rice singlet and triplet states was observed by the photoluminescence (PL) and the optical absorption in the single crystal NiPS<sub>3</sub> [1]. The locality of NiS<sub>6</sub> cluster based on the cluster model calculation was expected to show a stability of the coherent behavior against to the disturbance in the magnetically ordered system. Here, we newly synthesized the antiferromagnetic vdW Ni<sub>1-x</sub>Cd<sub>x</sub>PS<sub>3</sub> which have the non-magnetic dopant Cd replaced in the Ni sites homogeneously throughout the whole crystal. The lattice constant c extracted from the XRD pattern expanded linearly, changing by 0.6 % from x = 0 to 0.1, following the Vegard’s law. From the PL and absorption measurement, we observed that the coherent behavior of magnetic exciton peak shows high sensitivity to the dopant concentration where the Neel temperature relatively maintained showing a linear decrement. Here, we emphasize that we showed the decoherence behavior from the linewidth and peak suppression starts to change drastically even in the magnetically ordered ground state where the non-magnetic dopant broke the spin order locally. Additionally, we simulated the magnetic ground state for doped systems and the magnon linewidth broadening was compared with that from the optical probes. We expect that our work will provide novel magnetic systems with spin ordering for a deeper understanding of the magnetic exciton.<br/><br/>[1] S. Kang et al., Nature 583, 285 (2020)