$V_2O_3$ 薄膜中超快应变的各向异性：界面钳制下的非平衡相变
Anisotropy of Ultrafast Strain in $V_2O_3$ Thin Films: Out-of-Equilibrium Phase Transitions under Interfacial Clamping
浏览论文内容
中文总结 AI 辅助
通过方位分辨时间分辨X射线衍射，发现界面钳制在V2O3薄膜超快光致相变中作为静态选择器，决定各向异性应变动力学。
中文摘要 AI 辅助
关联材料中的超快光致绝缘体-金属转变通常由晶格畸变介导，但界面晶格约束在塑造非平衡路径中的作用在很大程度上仍未得到探索。我们使用方位分辨的时间分辨X射线衍射来追踪c切蓝宝石上颗粒状V$_2$O$_3$薄膜中取向相关的应变动力学，其中热膨胀失配施加了各向异性的界面应变。在热转变过程中，(110)$_H$应变的方位角分布发生曲率反转，直接证明了六方基面晶格（a$_H$,b$_H$）的部分钳制。在反铁磁绝缘相的光激发之后，结构响应仍然受钳制限制：弱约束的晶粒族达到金属态特征的完全基面收缩，而强约束的晶粒族表现出大幅减小的畸变。通量依赖的测量进一步将转变分数与钳制限制的晶格畸变区分开来。我们的结果表明，界面钳制充当超快相切换的静态选择器，并为量化异质结构中的各向异性应变动力学提供了一条通用途径。
英文摘要
Ultrafast photoinduced insulator-to-metal transitions in correlated materials are often mediated by lattice distortions, yet the role of interfacial lattice constraints in shaping nonequilibrium pathways remains largely unexplored. We use azimuth-resolved time-resolved X-ray diffraction to track orientation-dependent strain dynamics in granular V$_2$O$_3$ thin films on c-cut sapphire, where thermal-expansion mismatch imposes anisotropic interfacial strain. Across the thermal transition, the azimuthal profile of the (110)$_H$ strain inverts curvature, providing direct evidence of partial clamping of the hexagonal basal-plane lattice (a$_H$,b$_H$). After photoexcitation of the antiferromagnetic insulating phase, the structural response remains clamp-limited: weakly constrained grain families reach the full basal-plane contraction characteristic of the metallic-like state, whereas strongly constrained families exhibit a strongly reduced distortion. Fluence-dependent measurements further disentangle transformed fraction from clamping-limited lattice distortion. Our results show that interfacial clamping acts as a static selector for ultrafast phase switching and provide a general route to quantify anisotropic strain dynamics in heterostructures.
