Publications Repository - Helmholtz-Zentrum Dresden-Rossendorf

We present a ³¹P NMR investigation of BaCdVO(PO₄)₂ focusing on the nearly saturated regime between μ₀H_c1 = 4.05 T and μ₀H_c2 = 6.5 T, which used to be considered a promising candidate for a spin-nematic phase. NMR spectra establish the absence of any dipolar order there, whereas the weak field dependence of the magnetization above H_c1 is accounted for by Dzyaloshinskii-Moriya interaction terms. The low-energy spin dynamics (fluctuations), measured by the nuclear spin-lattice relaxation rate T₁ ⁻¹, confirms the continuity of this phase and the absence of any low-temperature phase transition. Unexpectedly, the spin dynamics above H_c1 is largely dominated by two-magnon processes, which is expected above the saturation field of a spin-nematic phase, but not inside. This shows that BaCdVO(PO₄)₂ is indeed close to a spin-nematic instability; however, this phase is not stabilized. We thus confirm recent theoretical predictions that the spin-nematic phase can be stabilized, at most, in an extremely narrow field range close to saturation or is rather narrowly avoided [Jiang et al., Phys. Rev. Lett. 130, 116701 (2023)].