CAREER: New Ferromagnetic Metals

Arizona State University, Scottsdale AZ

Investigators

Abstract

This CAREER project is focused on giant and colossal magnetoresistance (GMR and CMR) materials, and in particular on the discovery and characterization of new bulk half metals and GMR materials with increased structural and chemical complexities in a broad range of compounds, including chalcogenides, the Zintl compounds and intermetallics. For example, the half-metallic state in the thiochromates, such as ACrS3, A2CrS4, A2/3Cr2S4, A4CrS7 and A6Cr2S11 (A = rare-earth and/or alkaline-earth metals), will be obtained by chemically controlling the mixed-valence states and double exchange interactions between chromium ions. It is also proposed to induce the GMR effect in LnMn1-xSb2 and LnMnSi2 (Ln = rare-earth metals, Mn=manganese, Sb=antimony, Si=silicon), whose structures are formed by alternate stacking of magnetic and nonmagnetic layers. Finally, by strategically reducing the covalent bond strength around the transition metals and/or changing the electron concentrations, we will explore new magnetic intermetallics. By carrying out these projects, students will acquire an excellent understanding of chemical and electronic structures of materials, and of experimental skills required for the preparation and characterization of solid sate compounds. More importantly, the students will learn where various materials properties come from in chemical terms, so that they will be capable of rational design of new functional materials in their synthetic research. Overall, success in our research will provide new functional ferromagnetic materials that can be utilized in fabrication of novel electronic devices, and also will produce young materials researchers that will eagerly tackle interdisciplinary problems in materials sciences. In our modern society, advances in technology depend more than ever on the discovery and development of useful new materials, and solid-state chemistry has played an important role in the areas of catalytic, electronic, magnetic and optical materials research. This project in experimental solid-state chemistry will provide new magnetic materials with great promise for new devices with unprecedented functionalities, collectively under the name of "spin-electronics." Spin-electronic devices not only control the electrical signals (conventional electronic devices), but also manipulate the electron spins, a fundamental quantum mechanical property of electrons, which can immensely increase the capacity of data processing and storage even with current semiconductor manufacturing technology. Novel magnetic materials such as giant magnetoresistance (GMR) materials and half-metals which have much desired characteristics for spin-electronics applications will be discovered. By carrying out this research, students will acquire a good understanding of structure-property relationships of materials, as well as experimental skills for preparation and characterization of solid sate materials. More importantly, the students will learn where various useful materials properties come from in a "chemical" language, so that they will be capable of designing and synthesizing new functional materials in their future synthetic research. Overall, success in our research will provide new functional ferromagnetic materials that can be utilized in fabrication of novel electronic devices, and also will produce young materials researchers that will eagerly tackle interdisciplinary problems in materials sciences.