Magnetic Properties of Co 2 MnSb 1-x Sn x Thin Films

1. Magnetic Properties of Co2MnSb1-xSnx Thin Films Shane Stadler, Southern Illinois University, DMR-0545728 Highly spin-polarized materials have been of intense interest due to their potential impact on the development of spintronic devices. Among the various candidate half-metals (i.e., 100% spin-polarized materials), much attention has been given to some full Heusler alloys such as Co2MnSi, and also to substituted Heuslers such as Co2MnSb1-xSnx, due to theoretical predictions of their half-metallic properties. Using pulsed laser deposition, we have grown a series of substituted Heusler alloys (Co2MnSb1-xSnx) as a function of composition, temperature, and thickness, and on various substrates. One goal of this part of the project is to understand the structural and magnetic properties, including the magnetic anisotropy, and element-specific magnetic and electronic structures. Rotational magneto-optical Kerr effect MOKE (Fig. 1) and angle-dependent squareness (Fig. 2) measurements reveal an anisotropy of mixed four-fold and uniaxial contributions. In addition, Fourier analysis of the ROTMOKE data show that other terms also contribute to the total anisotropy. Fig. 1. (Upper) Rotational MOKE (obtained using the ROTMOKE method) for Co2MnSb1-xSnx. (Lower) Corresponding Fourier coefficients of the data. From these data, we can obtain information regarding the various mechanisms that contribute to the magnetic anisotropy. Fig. 2. Squareness of the hysteresis loops for Co2MnSb as a function applied field angle measured with longitudinal MOKE. These films exhibit complex anisotropy effects that depend on many factors including growth parameters and substrate characteristics.

2. Spreading the joy of magnetic materials science Shane Stadler, Southern Illinois University, DMR-0545728 A New Course As a part of the broader impact goals, I have developed a new class entitled Magnetism and Magnetic Materials I & II. The class is designed for upper level undergraduate students in physics, chemistry and engineering, and is divided into two parts: Part I is dedicated to the theory of magnetism and magnetic materials and addresses fundamental magnetism through applications of magnetic materials. Part II focuses on synthesis and measurement techniques, and has a corresponding laboratory component. Part I was taught once, and will be taught again in Spring 2008. Part II will be developed in the Summer of 2008 and offered as a course in Fall 2008. (see the notes page for some significant developments!). Recruiting from Underrepresented Groups Although our research group is relatively small (3+ graduate students and 4+ undergraduates), we have had reasonable success attracting students from underrepresented groups. Over the past year, we have had three graduate students working in our group (one is female), and four undergraduates (two females—one is African-American, one African-American male, and one Hispanic male).