AI 中文总结
研究通过对块状 CrI₃ 样品做高分辨率磁致伸缩实验及基于第一性原理的磁弹性计算，阐明单轴晶格应变对磁性的作用，量化相关参数的单轴应变依赖性，可通过块状单晶实验研究少层 CrI₃ 的磁弹性耦合。
AI 中文摘要
范德华半导体 CrI₃ 单层中持久的铁磁长程有序为基于二维量子磁体的自旋电子学应用开辟了新途径。在制造此类器件时，组成材料不可避免地会受到各向异性应变，这会改变其固有电子特性。虽然有理论研究数值探究了双轴面内应变对 CrI₃ 的影响，但实验大多局限于静水压力应用。本文通过对块状 CrI₃ 样品进行高分辨率磁致伸缩实验及基于第一性原理的磁弹性计算，来阐明单轴晶格应变对磁性的作用。数据表明 CrI₃ 的磁致伸缩对表面效应异常敏感，能分别研究面内和面外应变在居里温度 T₁ = 61K 时出现的体铁磁（BFM）相和低于 T*≈50K 的表面反铁磁（SAFM）相中的影响。特别地，量化了表面层间耦合 J⊥SAFM 和表面自旋翻转场 B* 的单轴应变依赖性，其比 BFM 相中的应变效应大 30 倍左右。这种大磁致伸缩响应使我们能通过块状单晶实验研究少层 CrI₃ 的磁弹性耦合，而无需剥离。
英文摘要
The persistence of ferromagnetic long-range order in monolayers of the van der Waals semiconductor CrI$_3$ opens new routes for spintronic applications based on two-dimensional quantum magnets. In the fabrication of such devices, the constituent materials inevitably experience anisotropic strain, which modifies their intrinsic electronic properties. At the same time, strain can serve as a powerful tuning parameter, driving the material to desired regimes. While several theoretical studies have investigated the effect of biaxial in-plane strain on CrI$_3$ numerically, experiments are widely limited to the application of hydrostatic pressure. Here, we perform high-resolution magnetostriction experiments on bulk CrI$_3$ samples, and \textit{ab-initio}-based magnetoelastic calculations, to elucidate the role of uniaxial lattice strain on the magnetic properties. Our data show that magnetostriction in CrI$_3$ is unexpectedly sensitive to surface effects, which enables us to investigate the influence of in-plane and out-of-plane strain separately, in both the bulk ferromagnetic (BFM) phase emerging at $T_{\rm C}=61\,\mathrm{K}$ and the surface antiferromagnetic (SAFM) phase below $T^* \simeq 50\,\mathrm{K}$. In particular, we quantify the uniaxial strain dependence of the surface interlayer coupling $J^{\rm SAFM}_{\perp}$ and the surface spin-flip field $B^*$, which drastically exceed the strain effects in the BFM phase by a factor of $\sim 30$. The large magnetostrictive response allows us to study the magnetoelastic coupling in few-layer CrI$_3$ through experiments on bulk single crystals, without requiring exfoliation.
Comments23 pages, 14 figures
