Low-energy excitations and magnetic anisotropy of the layered van der Waals antiferromagnet Ni${}_2$P${}_2$S${}_6$

Abstract

The quasi-two-dimensional antiferromagnet Ni${}_2$P${}_2$S${}_6$ belongs to the family of magnetic van der Waals compounds that provides a rich material base for the realization of fundamental models of quantum magnetism in low dimensions. Here, we report high-frequency/high-magnetic field electron spin resonance measurements on single crystals of Ni${}_2$P${}_2$S${}_6$. The results enable one to reliably determine the positive, "easy"-plane type of the single ion anisotropy of the Ni${}^{2+}$ ions with the upper limit of its magnitude $\lesssim 0.7$ meV. The resonance response reveals strongly anisotropic spin fluctuations setting in shortly above the Néel temperature $T_{\mathrm{N}}=158$ K and extending in the antiferromagnetically ordered state down to low temperatures. There, a low-energy magnon excitation gapped from the ground state by only $\sim 1$ meV was found. This magnon mode may explain unusual low temperature relaxation processes observed in a latest nuclear magnetic resonance experiments and together with the estimate of the single ion anisotropy they should enable setting up a realistic spin model for an accurate description of magnetic properties of Ni${}_2$P${}_2$S${}_6$.

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Cited by in corpus (11)

• The magnetic dynamics of NiPS${}_3$
• Spin wave Hamiltonian and anomalous scattering in NiPS${}_3$
• Observation of three-state nematicity and domain evolution in atomically-thin antiferromagnetic NiPS3
• Magnetic anisotropy and low-energy spin dynamics in the van der Waals compounds Mn${}_2$P${}_2$S${}_6$ and MnNiP${}_2$S${}_6$
• Direct Observation and Analysis of Low-Energy Magnons with Raman Spectroscopy in Atomically Thin NiPS3
• Electron Spin Resonance Spectroscopy on Magnetic Van der Waals Compounds
• Evolution of the spin dynamics in the van der Waals system $M_{\text{2}}$P${}_{\text{2}}$S${}_{\text{6}}$ (${\mathbf{M}}_{\text{2}}$ = Mn${}_{\text{2}}$, MnNi, Ni${}_{\text{2}}$) series probed by electron spin resonance spectroscopy
• Magnetic-field tuning of the spin dynamics in the quasi-2D van der Waals antiferromagnet CuCrP${}_2$S${}_6$
• Ultrafast Dynamics of Spin-Orbit Entangled Excitons Coupled to Magnetic Ordering in van der Waals Antiferromagnet NiPS3
• Spin Wave Dispersion of the van der Waals Antiferromagnet NiPS${}_3$
• Stabilization of zigzag order in NiPS${}_3$ via positive biquadratic interaction