论文标题
观察巨型表面第二谐波生成，并在范德华（van der waals）抗fiferromagnet feps $ _3 $中耦合到nematic Orders
Observation of giant surface second harmonic generation coupled to nematic orders in the van der Waals antiferromagnet FePS$_3$
论文作者
论文摘要
第二次谐波生成已应用于原子薄的材料中的晶格，电子和磁性专有。但是，材料产生大信号通常需要反转对称性破裂。在这项工作中，我们报告了一个巨大的第二次谐波一代，该一代在几层中心对称FEP $ _3 $的情况下低于Néel温度。层依赖性研究表明检测到的信号来自表面的二阶非线性。磁性诱导的表面第二谐波响应是两个数量级的数量级，比其他磁系统中报道的大量级数大，表面非线性易感性达到0.08--0.13 nm $^2 $^2 $/v，在2 L--5 L样品中达到。通过梳理线性二色性和第二次谐波生成实验，我们进一步证实了巨大的第二次谐波生成与由三个可能的锯齿形抗磁力磁性结构域形成的列级耦合。我们的研究表明，表面第二次谐波也是研究中心对称性原子较薄材料中的抗铁磁态的敏感工具。
Second harmonic generation has been applied to study lattice, electronic and magnetic proprieties in atomically thin materials. However, inversion symmetry breaking is usually required for the materials to generate a large signal. In this work, we report a giant second-harmonic generation that arises below the Néel temperature in few-layer centrosymmetric FePS$_3$. Layer-dependent study indicates the detected signal is from the second-order nonlinearity of the surface. The magnetism-induced surface second-harmonic response is two orders of magnitude larger than those reported in other magnetic systems, with the surface nonlinear susceptibility reaching 0.08--0.13 nm$^2$/V in 2 L--5 L samples. By combing linear dichroism and second harmonic generation experiments, we further confirm the giant second-harmonic generation is coupled to nematic orders formed by the three possible Zigzag antiferromagnetic domains. Our study shows that the surface second-harmonic generation is also a sensitive tool to study antiferromagnetic states in centrosymmetric atomically thin materials.
