Speaker: Dr. Ruijuan Xu, Stanford University

Speaker:  Dr. Ruijuan Xu, Department of Applied Physics, Stanford University

Title:  Controlling ferroelectricity at the nanoscale: from oxide heterostructures to freestanding crystalline membranes

Abstract

Complex oxides are fascinating material systems exhibiting a diverse set of electrical, magnetic, and thermal properties. In particular, ferroelectric oxides with an electrically switchable polarization and large dielectric and piezoelectric responses are considered as critical components for next-generation low-power logic devices, non-volatile memories, and nanoscale sensors and actuators, etc. Recent advances in thin-film synthesis techniques including the synthesis of oxide heterostructures and crystalline membranes have provided opportunities for realizing novel functionality in ferroelectrics. In this talk, I will show the ability to enable new device capabilities and emergent properties in the oxide heterostructures and crystalline membranes. First, I will introduce the kinetic control of ferroelectric switching pathways to create multiple non-volatile polarization states in (111)-oriented PbZr_0.2Ti_0.8O₃/SrTiO₃ heterostructures. Such switching phenomena transcend the bi-stability of ferroelectric polarization and hold promise for multi-state functional applications. Second, I will introduce our discovery of strain-induced ferroelectricity in quantum paraelectric SrTiO₃ crystalline membranes, which reveals enormous potential of employing membranes to create and enhance ferroelectricity in environmentally benign lead-free oxides.

Speaker bio

Dr. Ruijuan Xu is a postdoctoral fellow working with Prof. Harold Y. Hwang in the Department of Applied Physics at Stanford University. She received her Ph.D. in Materials Science and Engineering from the University of California, Berkeley, advised by Prof. Lane W. Martin. She was awarded the Stanford GLAM Postdoctoral Fellowship (2018), the Gareth Thomas Materials Excellence Award (2016), the Chinese Government Award for Outstanding Students Abroad (2015), and the Lam Research Fellowship (2015). Her research work focuses on the design, synthesis, and characterization of oxide thin-film heterostructure and freestanding crystalline membranes with emergent phenomena and new functionalities for next-generation nanomechanical, electromechanical, and magnetoelectric applications.