Qi Li

Associate Professor Qi Li is a condensed matter physicist studying a number of thin film electronic and electromagnetic phenomena. The early part of her career at the University of Maryland, Bellcore and finally Penn State was spent studying high Tc superconducting oxide thin film and superlattices. Recent efforts have focused on the unique magnetoresistance properties of certain thin film oxide materials and spin injection effect. Prof. Li uses pulsed laser deposition (PLD) and laser MBE to deposit rare earth- (and alkaline earth-) doped manganese oxide films onto single crystal substrates. The substrates are chosen with intentional lattice mismatches to induce 1-2% strain at the oxide-substrate interface. The application of an external magnetic field will dramatically change the resistance of the films, which is not present in single crystal or unstrained samples. Their results suggest that the magnetic domain boundaries are playing a larger role in her materials. In addition to the insight these materials may provide at the fundamental level, there may be practical applications in sensor and magnetic storage technologies. Prof. Li also uses the materials for injecting spins into other materials as they have very high degree of spin polarization to study spin diffusion process, which is an important element in Spintronics.

Dark field TEM image of the
Pr0.7Sr0.3MnO3 thin film on a single crystal LaAlO3 substrate

Professor Li currently collaborates with both experimentalists such as Beth Dickey (MATSE) and theoretical modelers Long-qing Chen (MATSE). She is anxious to collaborate with anyone at Penn State that can grow single crystal piezoelectric materials that may permit her to tune the interface strain in her magnetoresistant materials and possibly learn more about how they work. Anyone interested in learning more about Professor Li is encouraged to contact her directly at Validate to view contact info or visit her webpage at http://www.personal.psu.edu/qil1/.

Two recent publications dealing with the research discussed here are available online.