易平面范德华磁体CrCl₃中的短程磁序和多阶段相变
Short-range magnetic order and multi-stage phase transitions in the easy-plane van der Waals magnet CrCl$_3$
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中文总结 AI 辅助
研究准二维易平面范德华磁体CrCl₃，结合实验测量与理论计算分析其自旋关联及多阶段磁转变，揭示了室温下局域磁矩、不同温度下的磁序变化及层间交换相互作用的温度驱动交叉等特性。
中文摘要 AI 辅助
我们研究了准二维易平面范德华磁体CrCl₃中自旋关联的演化和多阶段磁转变的性质。通过结合宽带铁磁共振（FMR）光谱和直流SQUID磁强计对机械剥离的微薄片进行测量，并利用非局域动态平均场理论（DFT+DMFT）计算，分析了CrCl₃中的长程和短程磁序。实验上，SQUID和FMR测量证实了冷却时交叉到自旋极化相并随后转变为反铁磁基态的存在，但在远高于磁有序温度的温度下显示出稳健的短程关联。理论上，我们表明在室温下存在高度稳定的局域磁矩，由于宽莫特带隙，室温寿命τ为130 - 300 ps。低于室温时，面内关联长度ξ的快速增长表明形成了与实验观察一致的强短程磁序。我们还获得了层间交换相互作用的温度驱动交叉，其在高温下为正（铁磁），在低温有序相中为负（反铁磁）。
英文摘要
We investigate the evolution of spin correlations and the nature of the multi-stage magnetic transition in the quasi-two-dimensional easy-plane van der Waals magnet $\rm CrCl_3$. By combining broadband ferromagnetic resonance (FMR) spectroscopy and DC SQUID magnetometry on mechanically exfoliated micro-flakes with non-local dynamical mean-field theory (DFT+DMFT) calculations, we analyze both long- and short range magnetic order in CrCl$_3$. Experimentally, SQUID and FMR measurements confirm the presence of the crossover to a spin polarized phase with the subsequent transition into an antiferromagnetic ground state upon cooling, but show robust short-range correlations at temperatures far above the magnetic ordering temperatures. Theoretically, we show the existence of highly stable local magnetic moments at room temperature, with a giant room temperature lifetime $τ$ of 130--300 ps due to a wide Mott bandgap. Below room temperature, a rapid growth of the in-plane correlation length $ξ$ signals the formation of strong short range magnetic order consistent with the experimental observations. We also obtain a temperature-driven crossover of the interlayer exchange interaction, which changes from positive (ferromagnetic) at high temperatures to negative (antiferromagnetic) in the low-temperature ordered phase.
