Education:

• Ph.D. in physics, 2003, the Johns Hopkins University.
• B.S. in physics, 1997, Peking University.

Professional Experiences:

• 09/2012 -- present, Associate Professor, Department of Physics and Astronomy, University of Delaware, Newark, DE
• 07/2020 -- 06/2024, Graduate Program Director, Department of Physics and Astronomy, University of Delaware, Newark, DE
• 09/2006 -- 08/2012, Assistant Professor, Department of Physics and Astronomy, University of Delaware, Newark, DE
• 07/2003 -- 08/2006, CNM Distinguished Postdoctoral Fellow, Materials Science Division, Argonne National Laboratory, Argonne, IL

Research description:

Yi Ji operates the Mesoscopic Spintronics Lab in the Department of Physics and Astronomy at the University of Delaware. Spintronics means spin-based electronics and has become an active area of study since the 1990s. Spin is a fundamental quantum property of electrons and is associated with a tiny and fixed amount of magnetic moment. A spin current is a flow of collectively spin-polarized electrons in a solid state material. The goal of spintronics research is to produce ideas for novel, energy efficient, ultrafast, and high-density data storage and processing technologies. In the pursuit of this practical goal, physicists need to understand the basic physical processes related to spins. 

Our research explores the injection, transport, detection, and functionality of spin currents in lithographically patterned mesoscopic metallic structures commonly known as nonlocal spin valves (NLSVs). A unique feature of the NLSV system is that a pure spin current, without a net charge current, can be generated. A pure spin current can be technologically useful because of its non-invasive and energy efficient nature. It also allows for detailed studies of the ubiquitous spin relaxation processes in materials. Efforts have been dedicated to enhancing the spin injection efficiency across interfaces and the spin relaxation lengths in materials, and encouraging results have been systematically achieved. Other recent and ongoing research topics include spin transfer torque (STT) switching by a pure spin current, the spin-Hall effects, anisotropic spin relaxation and its origin, tunability of spin current, and quantitative understanding of the Kondo spin relaxation. 

Work in the Mesoscopic Spintronics Lab is heavily experimental and hands on. Researchers use advanced instrumentation such as thin film deposition systems, electron-beam lithography, microscopy, and variable temperature magneto-transport systems. Some experimental systems were designed, assembled, and programmed by Yi Ji and his students. In addition to our own laboratory equipment, we also rely on the University of Delaware Nanofabrication Facilities (UDNF).

Yi Ji's professional publications can be accessed via the google scholar, ORCiD, or Web of Science researcher profile link below.

Google Scholar
ORCiD
Web of Science researcher profile

Equipment in the Mesoscopic Spintronics Lab

Ph.D. Recipients Supervised

• Xingyu Shen, Ph.D., 2023 (Subsequent position: Staff Engineer, Western Digital; currently with Western Digital)
  
• Yunjiao Cai, Ph.D., 2019 (Subsequent position: Senior Data Scientist, JP Morgan Chase; currently with JP Morgan Chase)
• Fatih Kandaz, Ph.D., 2018 (Subsequent position: Faculty at Gebze Technical Univ., Turkey; currently with Gebze Technical Univ.)
• Chuan Qin, Ph.D., 2017 (Subsequent position: Staff Engineer, Western Digital; currently with Western Digital)
• Shuhan Chen, Ph.D., 2015 (Subsequent position: Postdoc, Purdue Univ.; currently with Western Digital)
• Han Zou, Ph.D., 2012 (Subsequent position: Postdoc, Hitachi Global Storage Technologies; currently with Meta)
• Xiaojun Wang, Ph.D., 2010 (Subsequent position: Postdoc, Hitachi Global Storage Technologies; currently with Lumentum)