Elastic Strain Engineering for unprecedented materials properties
Professor Ju Li, Massachusetts Institute of Technology
Strain Engineering uses strain to guide the interactions of material structures with electrons, photons, etc. and control energy, mass and information flows. The success of Strained Silicon technology today harbingers what Strain Engineering may do for human civilization in the future, with potential breakthroughs in electronics, photonics, ferroics, superconductivity, catalysis, sensing, etc. [MRS Bulletin 39 (2014) 108] In this talk I will give examples of exploiting the strain design space of low-dimensional materials. Homogenous and inhomogeneous elastic strain, bending, interlayer twist and slip [Nano Letters 15 (2015) 1302] lead to tunable, low-energy artificial atoms, artificial superlattices and pseudoheterostructures that can regulate quasiparticle motion. Strain also governs ferroelastic and band topology transitions in these materials [Science 346 (2014) 1344; Nature Communications 7 (2016) 10843]. Lastly, we demonstrate production of kilogram-scale nanowires under large tensile elastic strain, that leads to improved superconductivity. By controlling the strain tensor and strain gradient statically or dynamically, one opens up a much larger parameter space - on par with alloying - for optimizing the functional properties of materials, which imparts a new meaning to Feynman’s statement “There's Plenty of Room at the Bottom”.