EAPSI:Investigation of the Unconventional Superconducting Mechanism in Li0.9Mo6O17

Lawson Benjamin J, Ypsilanti MI

Investigators

Abstract

The discovery and understanding of new materials has driven technology development in the computer age. Research on the properties of semiconductors has laid the foundation for modern computer electronics. Better understanding of metals and insulators has enabled micro-fabrication and energy efficient technology. The discovery of the superconductor has lead to the hope of power transfer without energy loss. This project investigates an exotic superconducting material, Li0.9Mo6O17, under one of the leading scientists in the field of unconventional superconductors, Professor Yuji Matsuda from Kyoto University. This material shows some unusual low-dimensional properties that are not well understood. This project will clarify those unusual properties by probing the material with a sharp needle, which has a tip consisting of only a few atoms. By running electricity through the needle in a very cold environment, the nature of superconductivity in Li0.9Mo6O17 can be revealed. Better understanding of this material's properties will lead to an advancement of the field of unconventional superconductors and has promise to impact the future of electronics and computing. The objective of the proposed research is to determine the superconducting mechanism of the quasi-1D crystal Li0.9Mo6O17. This crystal has been proposed to be a Luttinger Liquid, an exotic state of matter where the electrons separate into independent charge and spin waves. Many studies have been done on Li0.9Mo6O17 in the normal state revealing exciting new physics. However, there is still much to be learned about the superconducting state of Li0.9Mo6O17. There is some evidence suggesting that Li0.9Mo6O17 is an unconventional spin-triplet superconductor, but a detailed study of the superconducting gap, which would elucidate the superconducting mechanism, has not been done. The PI, under the mentorship of Professor Yuji Matsuda, will grow high quality single crystal Li0.9Mo6O17 and perform Scanning Tunneling Microscopy (STM) in the superconducting state. To perform the first STM measurements of Li0.9Mo6O17 in the superconducting state, the PI will employ STM with 3He refrigeration. An STM study of the superconducting gap will reveal if Li0.9Mo6O17 behaves according to unconventional spin-triplet superconductivity or some other mechanism. This award under the East Asia and Pacific Summer Institutes program supports summer research by a U.S. graduate student and is jointly funded by NSF and the Japan Society for the Promotion of Science.