学　术

　　报告人：王凌飞

　　时　间：2019年7月10日（周三）14:30

　　地　点：沙河校区 物理学院204

　　报告人简介：

　　2013年于中国科学技术大学获凝聚态物理博士学位；2013至2015年于阿卜杜拉国王科技大学从事博士后研究，2015至2017年于首尔国立大学从事博士后研究，2018至今于首尔国立大学担任研究助理教授。

　　从事氧化物薄膜、异质结和原型器件相关工作，2008年至今以第一作者和通讯作者在Nature 　　Materials、Advanced Materials、Nano letters 等期刊发表文章二十余篇，个人被引超过1000次，H因子15。

　　报告摘要：

　　Perovskite-structured SrRuO3 is a prototypical ferromagnetic metal with a Curie temperature of ~ 160 K.A fine balance between the electron-electron correlation and spin-orbit coupling in SrRuO3 gives rise to a variety of exotic physical properties, including itinerant ferromagnetism, non-Fermi liquid electrical transport, magnetic monopoles in momentum space, and tunable magnetic skyrmions.

　　Here, we will show our recent results about tunable real-space and reciprocal-space topological properties in SrRuO3 ultrathin films. In the first part, we will report the discovery of ferroelectrically tunable skyrmions in ultrathin BaTiO3/SrRuO3 bilayer heterostructures. In this epitaxial system, ferroelectric proximity effect at the BaTiO3/SrRuO3 heterointerface can trigger a sizable Dzyaloshinskii-Moriya interaction, thus stabilizing magnetic skyrmions with a diameter of ~100 nm. Thanks to the strong coupling between ferroelectric distortion and Dzyaloshinskii-Moriya interaction, we can achieve local, switchable, and nonvolatile control of both skyrmion density and thermodynamic stability.In the second part, we will focus on the highly tunable anomalous Hall effect in SrRuO3 single layers. We found the anomalous Hall coefficient exhibit a clear sign reversal as the SrRuO3 film thickness decreases to 4 unit-cells. This behavior is dominated by the non-trivial topology and large Berry curvature at the avoided crossing points in SrRuO3 band structure. By harnessing the step-flow growth mode and artificially inducing a thickness non-uniformity, we can further modulate such a reciprocal-space topology-dominated magnetotransport. At last, we will propose several experimental methods for identifying the differences between the skyrmion-induced topological Hall effect and thickness inhomogeneity induced anomalous Hall effect.