题目：Phase Transitions of Correlated Oxides and Neuromorphic Electronics

报告人：石建 教授

        美国伦斯勒理工学院材料科学与工程学院

时间：2019年12月20日（周五）下午13:30

地点：国家脉冲强磁场科学中心C204

报告摘要:

As the finest computing system in our planet, human brain outperforms IBM Blue Gene at many aspects (energy efficiency, memory capacity and computational speed). Inspired by biological neural systems, neuromorphic systems open up new computing paradigms to explore cognition, learning and limits of parallel computation. In our brains, synapse is believed to be responsible for the learning and memory behaviors. The success of synapse concept at software-level artificial neural networks in the applications of voice and image recognitions has been driving the search for their hardware counterpart – synaptic transistor. Here we emulate the synapse by using a strongly correlated oxide – SmNiO₃. The electronic properties of correlated oxides are exceptionally sensitive to the orbital occupancy of electrons. We show a new strategy – interstitial electron doping via chemical route - for realizing sharp phase transition in perovskite SmNiO₃. The electron configuration of eg orbital of Ni3+t_2g^6 e_g^1 in metallic SmNiO₃ is modified by injecting and anchoring an extra electron, forming a strongly correlated Ni2+t_2g^6 e_g^2 structure leading to the emergence of a new insulating phase. By this means, a reversible resistivity modulation greater than eight orders of magnitude (along with large change in optical band gap) is demonstrated at room temperature. A solid state synaptic proton-gated phase-change transistor is demonstrated based on this principle. With ionic liquid-gating SmNiO₃ transistor as an example, synaptic Spike-Timing-Dependent Plasticity (a popular learning algorithm in many synapses) is realized. The extreme sensitivity of electronic properties to dopants in correlated oxides make them a particularly suitable class of materials to realize artificial biological circuits that can be operated at and above room temperature and seamlessly integrated into conventional electronic circuits.

参考文献:

Nat Commun. 2014;5:4860; Nat Commun. 2013;4:2676; Nature 2016;534, 231; Nat. Commun. 2019; 10, 694; Adv. Mater. 2019.

报告人简介:

石建，伦斯勒理工学院材料科学与工程学院教授。2006年于西安交通大学获得材料科学与工程理学学士，2008年于美国密苏里大学哥伦比亚分校获得机械工程硕士学位，2012年于威斯康星大学麦迪逊分校获得材料学博士学位，2013年至2014年在哈佛大学从事博士后研究，2014年至今于伦斯勒理工学院材料科学与工程学院担任教授。主要研究方向是半导体材料和相变材料的生长和物理性能，曾获伦斯勒理工学院工学院卓越成就奖，2017年获得美国空军研究部优秀青年奖(AFOSR-YIP)，并担任Journal of Applied Physics顾问编辑。