摘要

Electric-field control of phase transformation with ion transfer is of great interests in materials science with enormous practical applications. Due to the strong electron-ion interaction, the ionic evolution would naturally have dramatic influence on material functionalities. In this talk, I will first present a reversible and nonvolatile electric-field control of oxygen and hydrogen ion evolutions within the model system of brownmillerite SrCoO2.5 by ionic liquid gating. Due to the selectively controllable ionic evolutions, we achieved a tri-state phase transformations among SrCoO2.5 and its counterpart of perovskite SrCoO3-δ and a hitherto-unexplored HSrCoO2.5 phase. Because of the extremely distinct magnetic, electrical and optical properties among these three phases, this result forms solid foundation for conceptually new tri-state magnetoelectric and electrochromic effects. Along this vein, we further demonstrate the manipulation of metal-insulator transition and enhanced superconductivity through electric-field induced protonation in WO3 and iron-based superconductors, respectively. Finally, using Co/SrCoO2.5 as model system, I will introduce a new strategy to achieve the room temperature electric-field control of magnetic state in the Co layer accompanied by the bipolar resistance switch. In this case, the electric field controlled oxygen evolution leads to oxygen ion accumulation (gating) at the interface, in the same manner as the conventional charge-gating device. As the consequence, the interfacial oxygen contents modulate the magnetic interaction within the Co surface layer and eventually results in the intriguing magnetoelectric coupling. We envision that the ionic evolution brings in a new tuning knob to manipulate the coupling and correlation between charge, spin, orbital and lattice degrees of freedom and paves a new playground for the discovery of novel materials and rich functionalities. 

报告人简介

于浦，清华大学物理系副教授、青年973首席科学家。1998-2005年在清华大学物理系获得理学学士、硕士学位。2005-2011年在美国加州大学Berkeley分校物理系取得博士学位。2011年至2012年在日本东京大学、理化学研究所从事博士后研究。2013年初任物理系助理教授，2017年初聘为副教授。2014年起兼任日本理化学研究所兼职研究员和研究组长。研究领域立足于凝聚态实验物理和材料科学的交叉领域，着重于研究功能氧化物薄膜等量子受限系统的新颖特性和物理机制，发表学术论文60余篇，文章总引用数5000 余次，H Index 31。受邀在著名学术会议（APS March Meeting 2次、MRS Meeting 4次）和研究机构做邀请报告 40 余次。

Host: Weidong Luo