MSE 298 Seminar (Zoom): Ion Beam Modification of High-temperature Superconductors for Nanoscale Quantum Devices

Zoom: Meeting ID https://ucsd.zoom.us/s/8425066501, Passcode: 587901

Abstract: In Feynman’s infamous 1959 lecture titled "There's Plenty of Room at the Bottom," he inspired and foreshadowed the emergence of nanoengineering. He suggested that finely focused electron and ion beams would aid our eyes and hands to precisely engineer structures at the atomic level. Currently, electron beam lithography systems and gallium-focused ion beams are ubiquitous in nanotechnology and can routinely be used to create structures of the order of tens of nanometers. However, the ability to scale to the sub-10 nm has been a technological challenge until the development of gas field ion sources (GFIS) over the past decade. The GFIS source utilizes a single crystal tungsten wire sharpened to just three atoms. Helium gas is field ionized by one of these atoms, creating a helium ion beam with diameter of only 0.25nm! This instrument is emerging as an important tool for sub-10nm structuring of materials. Helium ion beams have significant advantages. Helium is small and chemically inert, which allows it to be used for direct modification of materials properties without etching away material or employing resists. My research group has been utilizing GFIS for direct patterning of ceramic high-temperature superconducting materials for quantum electronics. The helium ion beam induces nanoscale disorder from irradiation into the crystalline structure, which converts the electrical properties of the material from superconductor to insulator. Insulating feature sizes of less than 2nm have been successfully demonstrated, and many unique novel devices have been realized. Much of this success is due to the irradiation sensitivity of electrical transport in high-temperature superconductors. This sensitivity results from loosely bound oxygen atoms (~1-8ev) in the crystal lattice that are easily displaced into interstitial or anti-site defects. I will describe details of the GFIS materials modification process and discuss new properties of nanoscale superconducting devices. In addition, I will highlight several applications in quantum sensing, and high frequency detection.

Bio: Professor Shane Cybart is the principal investigator of the Oxide Nano Electronics Laboratory at UC Riverside. He obtained a doctorate in materials science from UC San Diego in 2005 studying high-transition temperature Josephson devices. He continued his work in superconductive electronics as a postdoctoral research at UC Berkeley from 2006-2009. From 2009-2016, he worked as a scientist at UC Berkeley and San Diego developing oxide electronic devices for a diverse range of applications. In June 2016, he joined the Bourns College of Engineering at UC Riverside. He is currently an associate professor of electrical engineering and cooperating faculty in the Department of Physics and Materials Science Program. His group studies the basic science and applications of Josephson devices.