Magnetism of $\mathrm{NaYbS_2}$: From finite temperatures to ground state
Abstract
Rareearth chalcogenide compounds $\mathrm{ARECh_2}$ (A = alkali or monovalent metal, RE = rare earth, Ch = O, S, Se, Te) are a large family of quantum spin liquid (QSL) candidate materials. $\mathrm{NaYbS_2}$ is a representative member of the family. Several key issues on $\mathrm{NaYbS_2}$, particularly how to determine the highly anisotropic spin Hamiltonian and describe the magnetism at finite temperatures and the ground state, remain to be addressed. In this paper, we conducted an indepth and comprehensive study on the magnetism of $\mathrm{NaYbS_2}$ from finite temperatures to the ground state. Firstly, we successfully detected three crystalline electric field (CEF) excitation energy levels using lowtemperature Raman scattering technique. Combining them with the CEF theory and magnetization data, we worked out the CEF parameters, CEF energy levels, and CEF wavefunctions. We further determined a characteristic temperature of $\sim$40 K, above which the magnetism is dominated by CEF excitations while below which the spinexchange interactions play a main role. The characteristic temperature has been confirmed by the temperaturedependent electron spin resonance (ESR) linewidth. Lowtemperature ESR experiments on the dilute magnetic doped crystal of $\mathrm{NaYb_{0.1}Lu_{0.9}S_2}$ further helped us to determine the accurate $g$factor. Next, we quantitatively obtained the spinexchange interactions in the spin Hamiltonian by consistently simulating the magnetization and specific heat data. Finally, the above studies allow us to explore the ground state magnetism of $\mathrm{NaYbS_2}$ by using the density matrix renormalization group. We combined numerical calculations and experimental results to demonstrate that the ground state of $\mathrm{NaYbS_2}$ is a Diraclike QSL.
 Publication:

arXiv eprints
 Pub Date:
 June 2024
 DOI:
 10.48550/arXiv.2406.04819
 arXiv:
 arXiv:2406.04819
 Bibcode:
 2024arXiv240604819Z
 Keywords:

 Condensed Matter  Strongly Correlated Electrons
 EPrint:
 13 pages, 6 figures