Spin fluctuations, absence of magnetic order, and crystal electric field studies in the Yb³⁺-based triangular lattice antiferromagnet Rb₃ ⁢Yb⁢(VO₄)₂

Journal Article · Thu Sep 18 00:00:00 EDT 2025 · Physical Review B

DOI:https://doi.org/10.1103/ydpn-8wgf· OSTI ID:2998125

Sebastian, Sebin J. ^[1]; Kolay, R. ^[2]; B, Abhidev. ^[2]; Ding, Q.-P. ^[3]; Furukawa, Y. ^[3]; Nath, R. ^[2]

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1. Indian Institute of Science Education and Research (IISER), Thiruvananthapuram (India); Ames Laboratory, and Iowa State Univ., Ames, IA (United States)
2. Indian Institute of Science Education and Research (IISER), Thiruvananthapuram (India)
3. Ames Laboratory, and Iowa State Univ., Ames, IA (United States)

Here, we report a comprehensive experimental investigation of the structural, thermodynamic, static, and dynamic properties of a triangular lattice antiferromagnet Rb₃ ⁢Yb(VO₄)₂. Through the analysis of magnetic susceptibility, magnetization, and specific heat, complemented by crystal electric field (CEF) calculations, we confirm the Kramers' doublet with effective spin 𝐽_eff = 1/2 ground state. Magnetic susceptibility and isothermal magnetization analysis reveal a weak antiferromagnetic interaction among the 𝐽_eff = 1/2 spins, characterized by a small Curie-Weiss temperature (𝜃$$^{\textrm{LT}}_{\textrm{CW}}$$ ≃−0.26 K) or a reduced exchange coupling (𝐽/𝑘_B ≃ 0.18 K). The 51 V NMR spectra and spin-lattice relaxation rate (1/𝑇₁) show no evidence of magnetic long-range-order down to 1.6 K but reflect strong influence of CEF excitations in the intermediate temperatures. At low temperatures, 1/𝑇₁⁡(𝑇) shows pronounced frequency dependence and 1/𝑇₁ vs field at different temperatures follows the scaling behavior, highlighting the role of paramagnetic fluctuations. The CEF calculations using the point charge approximation divulge a large energy gap ( ∼18.61 meV) between the lowest and second lowest energy doublets, further establishing Kramers' doublet as the ground state. Our calculations also reproduce the experimental magnetization and specific heat data and indicate an in-plane magnetic anisotropy. These findings position Rb_3⁢ Yb(VO₄)₂ as an ideal candidate to explore intrinsic quantum fluctuations and possible quantum spin-liquid physics in a Yb³⁺-based triangular lattice antiferromagnet.

• Research Organization: Ames Laboratory (AMES), Ames, IA (United States)
• Sponsoring Organization: USDOE Office of Science (SC), Basic Energy Sciences (BES). Materials Sciences & Engineering Division (MSE)
• Grant/Contract Number: AC02-07CH11358
• OSTI ID: 2998125
• Journal Information: Physical Review B, Journal Name: Physical Review B Journal Issue: 10 Vol. 112; ISSN 2469-9950; ISSN 2469-9969
• Publisher: American Physical Society (APS)
• Country of Publication: United States
• Language: English