标题： 热电子驱动的双层FeSe结构膨胀和磁性坍缩 显示英文标题

标题： Hot Electron-Driven Structural Expansion and Magnetic Collapse in Bilayer FeSe

摘要： 量子现象源于光与物质在低维系统中的相互作用，对未来量子技术具有巨大的潜力。 在这里，我们使用包含非局部范德华相互作用和哈伯德修正的第一性原理计算，报告了由光激发的热电子引起的双层FeSe同时的结构膨胀和磁性崩溃。 我们的计算表明，虽然块体FeSe是顺磁性的，如实验所观察到的，但双层FeSe在低温下表现出强大的{\it 交错的}反铁磁序，具有每Fe的净位点磁化强度为$\sim 2.75~\mu_B$。 然而，增加光激发电子的密度系统地增强了内部电子熵，导致反铁磁序的完全崩溃，并伴随着层间距离的突然扩张。 我们的发现表明，可以通过超快激光激发精细调节FeSe薄膜的结构和磁性特性，为通过电子温度控制铁基化合物中的量子相提供了一条途径。 显示英文摘要

摘要： Quantum phenomena emerging from the interaction of light and matter in low-dimensional systems hold great potential for future quantum technologies. Here, using first-principles calculations incorporating non-local van der Waals interactions and Hubbard corrections, we report simultaneous structural expansion and magnetic collapse in bilayer FeSe induced by photoexcited hot electrons. Our calculations reveal that, while bulk FeSe is paramagnetic, as observed experimentally, double-layer FeSe exhibits robust {\it staggered} antiferromagnetic order at low temperatures with a net site magnetization of $\sim 2.75~\mu_B$/Fe. However, increasing the density of photoexcited electrons systematically enhances the internal electronic entropy, leading to a complete collapse of antiferromagnetic order accompanied by an abrupt expansion of the interlayer separation. Our findings suggest the structural and magnetic properties of FeSe thin films can be finely tuned via ultrafast laser excitation, offering a pathway to control quantum phases in iron-based compounds through electronic temperature.