Jeong Seung Gyo, Choi In Hyeok, Lee Seungjun, Oh Jin Young, Nair Sreejith, Lee Jae Hyuck, Kim Changyoung, Seo Ambrose, Choi Woo Seok, Low Tony, Lee Jong Seok, Jalan Bharat
Department of Chemical Engineering and Materials Science, University of Minnesota-Twin Cities, Minneapolis, MN 55455, USA.
Department of Physics and Photon Science, Gwangju Institute of Science and Technology (GIST), Gwangju 61005, Republic of Korea.
Sci Adv. 2025 Jun 27;11(26):eadw7125. doi: 10.1126/sciadv.adw7125.
Ultrafast light-matter interactions inspire potential functionalities in picosecond optoelectronic applications. However, achieving directional carrier dynamics in metals remains challenging due to strong carrier scattering within a multiband environment, typically expected for isotropic carrier relaxation. In this study, we demonstrate epitaxial RuO/TiO (110) heterostructures grown by hybrid molecular beam epitaxy to engineer polarization selectivity of ultrafast light-matter interactions via anisotropic strain engineering. Combining spectroscopic ellipsometry, x-ray absorption spectroscopy, and optical pump-probe spectroscopy, we revealed the strong anisotropic transient optoelectronic response at an excitation energy of 1.58 eV in strain-engineered RuO/TiO (110) heterostructures along both in-plane [001] and [1[Formula: see text] 0] crystallographic directions. Theoretical analysis identifies strain-induced modifications in band nesting as the underlying mechanism for enhanced anisotropic carrier relaxation observed at this excitation energy. These findings establish epitaxial strain engineering as a powerful tool for tuning anisotropic optoelectronic responses with near-infrared excitations in metallic systems, paving the way for next-generation polarization-sensitive ultrafast optoelectronic devices.
超快光与物质相互作用激发了皮秒光电子应用中的潜在功能。然而，由于在多能带环境中存在强烈的载流子散射，在金属中实现定向载流子动力学仍然具有挑战性，这种散射通常是各向同性载流子弛豫所预期的。在本研究中，我们展示了通过混合分子束外延生长的外延RuO/TiO(110)异质结构，以通过各向异性应变工程来设计超快光与物质相互作用的偏振选择性。结合椭圆偏振光谱、X射线吸收光谱和光泵浦-探测光谱，我们揭示了在应变工程化的RuO/TiO(110)异质结构中，沿面内[001]和[1[公式：见原文]0]晶体学方向，在1.58 eV激发能量下存在强烈的各向异性瞬态光电子响应。理论分析确定，能带嵌套中的应变诱导修饰是在该激发能量下观察到的增强各向异性载流子弛豫的潜在机制。这些发现确立了外延应变工程作为一种强大工具，可用于在金属系统中利用近红外激发来调节各向异性光电子响应，为下一代偏振敏感超快光电器件铺平了道路。
