[论文解读] Uniaxial strain tuned magnetism of the altermagnet candidate h-FeS

Weiliang Yao, Feng Ye+10 more|arXiv (Cornell University)|Feb 16, 2026

Iron-based superconductors research被引用 0

一句话总结

这项研究表明，在平面内单轴压应变通过重新平衡平面磁畴并降低自旋弯曲来抑制六方 FeS 中自发异常霍尔效应（AHE）和沿 c 轴的微小铁磁矩，所用证据来自输运、磁化、中子衍射和原位中子散射。

ABSTRACT

Altermagnets are collinear magnetic materials with 'alter'nating local crystalline environments, characterized by joint spin and crystalline symmetries that enable ferromagnetic-like transport properties but with vanishing net magnetization. Hexagonal FeS (h-FeS) is a recently identified altermagnet candidate that shows a spontaneous anomalous Hall effect (AHE) accompanied by a tiny net magnetization. Here, we show that both the spontaneous AHE and magnetization can be effectively suppressed by an in-plane compressive strain. Since neutron diffraction measurements show that the applied uniaxial strain only modifies the in-plane domain population but does not affect the in-plane magnetic structure, the major effect of the applied strain is to tune the small $c$-axis ferromagnetic moment. Our results demonstrate a strong correlation between the tiny net magnetization and the spontaneous AHE in h-FeS, and show that uniaxial strain provides an effective knob to tune both properties in this altermagnet candidate for spintronic applications.

研究动机与目标

• 研究平面内单轴应变如何影响 h-FeS 中的自发异常霍尔效应，该材料是一个 altermagnet 候选者。
• 确定应变是否能同时改变微小净磁化和 AHE。
• 阐明应变下自旋弯曲、畴结构与磁弹性效应之间的关系。

提出的方法

• 在平面内单轴应变下进行电输运测量，以提取自发 AHE 分量。
• 沿 c 轴的磁化测量，用以量化应变引起的铁磁矩改变。
• 在应变下进行中子衍射，监测磁畴占据和面内磁结构。
• 原位中子散射，探测自旋波隙及其应变依赖性。
• 对称性与晶场分析，用以解释应变诱导的局部 Fe 配位和自旋轨道耦合效应变化。

Figure 1: (a) Crystal structure of h-FeS above $T_{\rm{M}}$ . Two S octahedra surrounding Fe ions are explicitly shown. The upper left inset shows the Fe spin configurations inside the two octahedra, where the spins initially along the [ $1\bar{1}0$ ] direction exhibit a slight canting toward the Fe

实验结果

研究问题

• RQ1 平面内单轴应变是否抑制 h-FeS 的自发异常霍尔效应？
• RQ2 AHE 的抑制是否伴随沿 c 轴的微小磁矩变化？
• RQ3 单轴应变如何影响 h-FeS 的平面内磁畴占据和自旋弯曲？
• RQ4 自旋波隙与磁晶各向异性在 h-FeS 的应变响应中起何作用？

主要发现

• ab 面内的压应变逐渐抑制自发 AHE，在 T_M 之上对磁场依赖的普通霍尔和常规 AHE 没有实质性影响。
• 平面内压应变下，微小的沿 c 轴的铁磁矩（自旋弯曲）被削弱，表明应变抑制了弯曲。
• 中子衍射显示应变在 T_M 之上重新分配平面内磁畴，其中一个畴被强烈抑制，两个畴成为主导；在 T_M 以下，畴占比再度变得相近。
• 原子中子散射揭示的自旋波隙在温度升高时被有效抑制，与应变下畴再取向更容易一致。
• h-FeS 的压应磁系数在 160 K 时约为 ~10^-3 G/MPa，所观察的效应与磁弹耦合及自旋轨道耦合介导的弯曲相关。
• 自发 AHE 与微小净磁化高度相关，单轴应变作为两者的有效控制参数。

Figure 2: (a)-(d) Magnetic-field dependence of the Hall resistivity measured at selected temperatures under compressive strain applied along [ $1\bar{1}0$ ]. The solid line in (b) represents a linear fit to the data, as described in the text. For clarity, the data are vertically offset by 0.2 $\mu\O