1. National Science Foundation A Study of Half-Metallic Heusler Alloys Chad Berry, Berea College, DMR 1002627 Explanation: Half metals are metals that conduct only electrons of one spin orientation and act as an insulator or semiconductor to those of the opposite orientation. These materials are desirable in applications of spintronics (spin transport electronics), as they act as a source of polarizing the electric current into solely spin up or spin down electrons. If this polarization can occur, then the spin of the electron can be used, as opposed to the bulk charge that is currently utilized. Berea undergraduate student Kyle Godbey operating the arc discharge furnace Outcome: Researchers at Berea College synthesized Half-Metallic Heusler Alloys. Impact: Some of these alloys hold the potential to be used in Spintronics at room temperature.

2. National Science Foundation A Study of Half-Metallic Heusler Alloys Chad Berry, Berea College, DMR 1002627 The goal of this research is to explore the structural and magnetic properties of certain series of Heusler alloys. Specifically, the series Co 2-x Fe 1+x Z (Z = Si, Ge, Sn), where x is a value between zero and one. The idea is to examine the effect of the substitution of the X and Y site atoms with one another. XRD data of Co 2-x Fe 1+x Si XRD data of Co 2-x Fe 1+x Ge Heusler alloys are alloys of the form X 2 YZ, where X, Y, and Z can be any element. These alloys are ferromagnetic, and certain alloys may also be half metallic. The cause of this theoretical half metallicity at room temperature is the high Curie temperature and large band-gap at the Fermi energy level.

3. National Science Foundation A Study of Half-Metallic Heusler Alloys Chad Berry, Berea College, DMR 1002627 The process that was followed to produce the samples was perfected from input from the myriad of papers that have created these samples and samples similar to them. First, stoichiometric ratios of the constituent elements were measured out and mixed together in a mortar. Then, this mixture was placed in the MRF arc discharge furnace, and the atmosphere inside the chamber was flushed and filled with argon. During the course of the research, another series was chosen for investigation, this one being Co 2 FeGe 1-x Sn x ­. It was found that the Co 2 FeSn series could not be synthesized using the arc discharge method, so the germanium compound doped with tin was pursued until no single phase was observed.. XRD data of the Co 2 FeGe 1-x Sn x Lattice constant with varying x

4. National Science Foundation A Study of Half-Metallic Heusler Alloys Chad Berry, Berea College, DMR 1002627 The samples were then melted by the furnace, with the power needed depending upon the alloy being made. Once the sample was melted through, the ingot produced was removed from the chamber and pulverized using the hydraulic press, mortar and pestle. When the sample was a fine enough powder for x-ray diffraction (XRD), it was placed in the Philips X-Pert x-ray diffractometer for crystal identification. We are in the process of acquiring low temperature Mossbauer and magnetization data of the synthesized samples. M ö ssbauer spectrum of Co 2 FeSi VSM data of Co 2-x Fe 1+x Si