****Technical Abstract**** First-principles theory (DFT and beyond) will be used to screen thousands of half-metals and choose a set of experimentally-accessible starting materials. We will also develop models based on state-of-the-art Non-Equilibrium Green Functions to calculate their transport characteristics. Experimentally, we will synthesize the candidate materials, test their electrical, magnetic, and structural characteristics and compare to theoretical predictions. The results of this characterization will then be fed back to refine our theoretical methods. Promising materials will be tested with more advanced techniques (such as spin-polarized tunneling and local-electrode atom probe tomography), providing more detailed information for more advanced modeling. The most promising materials will be used in prototype TMR and (CIP/CPP)-GMR devices. A specific disruptive technology goal is the design, fabrication and demonstration of a low moment half-metal with perpendicular anisotropy and low magnetic damping ideally suited for STT-RAM. This will be accomplished through the tight circular work flow among rational design, computational verification, spin transport modeling, experimental characterization and device fabrication. Several interdisciplinary courses at UA and UVa will be developed to quickly incorporate lessons we have learned into the classroom and provide students with cutting-edge training. Software developed in the project will be deployed on the NSF NanoHUB.
In today's electronic devices electrons are manipulated through their electrical charge. However, electrons have another property called "spin". Electrons behave as if they were spinning about an axis. According to quantum mechanics the spin axis of an electron can point in only one of two directions, i.e. either "up" or "down". In most materials there are equal numbers of up and down electrons and usually both types respond to an electric field in the same way. In magnetic materials, however, the number of up and down spin electrons may be different and the two types of electrons may respond to electric fields in different ways. The most extreme example of this phenomenon is a "half-metal" - meaning that one set of electrons is a metal and the other set is an insulator. A specific technology goal is the design, fabrication and demonstration of a half-metal with carefully controlled magnetic properties tailored to meet the requirements of non-volatile magnetic memories (which aim to replace traditional RAM). We aim to provide an improved understanding of half-metals and magnetic materials in general, in particular how one can relate 'first-principles' calculations to experimentally accessible and technologically relevant materials and device parameters. This project will help to increase the STEM workforce by providing research experiences for undergraduates and high school students and will enhance its diversity through its composition and collaboration with HBCU faculty. Several interdisciplinary courses at UA and UVa will be developed to quickly incorporate lessons learned into the classroom and provide students with cutting-edge training.
