论文标题
Ni $ _2 $ P $ _2 $ S $ _6 $ $ {}}^{31} $ P NMR探测
Quasi-2D magnetic correlations in Ni$_2$P$_2$S$_6$ probed by ${}^{31}$P NMR
论文作者
论文摘要
详细的$ {}^{31} $ p核磁共振（NMR）测量在抗铁磁性的单晶上显示了反铁磁性范德华ni $ _2 $ _2 $ _2 $ _2 $ s $ _6 $。 NMR Shift $ K $与散装易感性$χ$的比例观察到了异常的故障。这种所谓的$ k $$ - $$χ$异常发生在$χ（t）$中的大峰值附近，从而暗示与已知为此最大负责的Quasi-2D磁相关性的联系。量子化学计算表明，晶体场能水平的减少效应不能负责$ k $$ - $$χ$异常。观察到了明显的平面内传输超精细耦合，这与拟议的Ni $ - $ S $ - $ NI SUPER-和NI $ - $ S $ - $ S $ -S $ - $ NI SUPER-SUPER-SUPER-SUPEPER-EXCHANGE耦合机制一致。磁化和自旋$ - $晶格放松率（$ t_1^{ - 1} $）的测量值表示Néel温度的磁场依赖性几乎没有。最后，$ t_1^{ - 1}（t）$证明由抗铁磁状态的三麦克农散射驱动的放松。
Detailed ${}^{31}$P nuclear magnetic resonance (NMR) measurements are presented on well-characterized single crystals of antiferromagnetic van der Waals Ni$_2$P$_2$S$_6$. An anomalous breakdown is observed in the proportionality of the NMR shift $K$ with the bulk susceptibility $χ$. This so-called $K$$-$$χ$ anomaly occurs in close proximity to the broad peak in $χ(T)$, thereby implying a connection to quasi-2D magnetic correlations known to be responsible for this maximum. Quantum chemistry calculations show that crystal field energy level depopulation effects cannot be responsible for the $K$$-$$χ$ anomaly. Appreciable in-plane transferred hyperfine coupling is observed, which is consistent with the proposed Ni$-$S$-$Ni super- and Ni$-$S$-$S$-$Ni super-super-exchange coupling mechanisms. Magnetization and spin$-$lattice relaxation rate ($T_1^{-1}$) measurements indicate little to no magnetic field dependence of the Néel temperature. Finally, $T_1^{-1}(T)$ evidences relaxation driven by three-magnon scattering in the antiferromagnetic state.
