Electron spin resonance on the spin-1/2 triangular magnet NaYbS₂

Abstract

The delafossite structure of NaYbS 2 contains a planar spin-1/2 triangular lattice of Yb 3+ ions and features a possible realisation of a quantum spin-liquid state. We investigated the Yb 3+ spin dynamics by Electron Spin Resonance (ESR) in singlecrystalline samples of NaYbS 2 . Very clear spectra with a well-resolved and large anisotropy could be observed down to the lowest accessible temperature of 2.7 K. In contrast to the ESR properties of other known spin-liquid candidate systems, the resonance seen in NaYbS 2 is accessible at low fields (< 1T) and is narrow enough for accurate characterisation of the relaxation rate as well as the g factor of the Yb 3+ spins.arXiv:1812.07871v1 [cond-mat.str-el]

Effective Spin-1/2 Moments on a Yb3+ Triangular Lattice: An ESR Study

“…2 demonstrates the temperature dependence of the ESR parameters being again very similar to NaYbS 2 [7] . The linewidth ∆B and the relaxation rates Γ show characteristic low-and high temperature behaviors: towards low temperatures a power law increase ∆B(T ) ∝ 1/T 3/4 and towards high temperatures an Orbach process ∆B ∝ 1/ exp(∆/k B T ) − 1 which includes population of the first excited crystalline-electric field doublet at an energy ∆ above the ground state [7]. Within data accuracy, no clear temperature dependence of the Γ anisotropy could be resolved.…”

“…We obtained and analyzed the ESR data of the above mentioned compounds in the same way as previously reported for NaYbS 2 [7]. All spectra are well-resolved and reveal a common characteristics for a J = 7/2 state of Yb 3+ in an crystal electric field environment with a R3m space group symmetry.…”

YbMgGaO4: A Triangular‐Lattice Quantum Spin Liquid Candidate

“…For NaYbS 2 , the single‐crystal sample is available and no long‐range magnetic transition was observed down to 260 mK . ESR spectra show the highly planar anisotropy of the Yb 3+ magnetic moments, with g ┴ = 3.19 and g ║ = 0.57 . And the gap between the ground and first‐excited CEF states is measured to be about 17 meV, much smaller than that of YbMgGaO 4 (≈39.4 meV).…”

“…[113] ESR spectra show the highly planar anisotropy of the Yb 3+ magnetic moments, with g ┴ = 3.19 and g ║ = 0.57. [113,114] And the gap between the ground and first-excited CEF states is measured to be about 17 meV, [113] much smaller than that of YbMgGaO 4 (≈39.4 meV). The small CEF gap makes the single-ion physics mix with the many-body-correlated physics in the moderate temperature range, and thus the reported Curie-Weiss behavior of the susceptibilities is unobvious.…”

Magnetic Properties of an Effective Spin-\(\frac{1}{2}\) Triangular-Lattice Compound LiYbS2

“…At temperatures considerably lower than the energy gap ∆ between the ground state and the first excited state doublet, the magnetic properties can be described by an effective spin-1 2 local moment. The values of ∆ are found to be ∼ 200, ∼400, and ∼ 180 K for NaYbS 2 [6,17], NaYbO 2 [7,8], and NaYbSe 2 [11,16], respectively. Low field studies reveal a QSL ground state with gapless excitations for both NaYbS 2 and NaYbO 2 .…”