CAREER: Seeking Half-Metallic Alloys

1. CAREER: Seeking Half-Metallic Alloys Shane Stadler, Southern Illinois University at Carbondale, DMR 0545728 Microwave magnetoelectric coupling and ferromagnetic resonance frequency tuning of a Co2MnSb/GaAs/PZN-PT heterostructure* Multiferroic (MF) materials exhibiting magnetoelectric (ME) effects have drawn considerable attention for both their fundamental physical behavior as well as for their potential in a new class of magnetoelectric devices. Among the numerous ongoing investigations, multiferroic metamaterials, constructed as multilayered or granular heterostructures, have drawn the most attention.MF heterostructures have indeed been shown to offer unique opportunities in the development of many new multifunctional devices, including electric-field-controlled (EFC) magnetic memory elements. Our current work explores the potential of electronically controlled multiferroic devices for use in microwave integrated circuits (MICs), while concurrently establishing the basic theoretical foundation allowing for the calculation of microwave tunability for heterostructures in general. We have grown a Co2MnSb/GaAs/PZN-PT multiferroic heterostructure (Fig. 1) for which we observed a large linear electric field tuning of microwave ferromagnetic resonance frequency (see Fig. 2), indicating a microwave tunability of ~44 MHz cm kV-1 and a converse magnetoelectric coupling coefficient of 9 Oe cm kV-1 . Fig. 1. Schematic diagram depicting the H and E fields within the Co2MnSb/GaAs/PZN-PT multiferroic heterostructure. Fig. 2. The variation of FMR absorption derivative with magnetic field for different electric field strengths, * Microwave magnetoelectric coupling and ferromagnetic resonance frequency uning of a Co2MnSb/GaAs/PZN-PT heterostructure, Y. Chen, A. Yang, M. R. Paudel, S. Stadler, C. Vittoria, and V. G. Harris(Submitted).

2. CAREER: Seeking Half-Metallic Alloys Shane Stadler, Southern Illinois University at Carbondale, DMR 0545728 BROADER IMPACTS (i) CLASS DEVELOPMENT: Magnetism and Magnetic Materials This new magnetic materials class was designed to target advanced undergraduate and graduate students across scientific disciplines that overlap with materials research. Interestingly, the level and subject material of the class indeed attracted a diverse set of students, and each time the class was offered it had to be tailored to the backgrounds, levels, and skills of the students. One goal of this class was to attract new and diverse students to the field of magnetism. As shown in the following chart, it seems that it has had the desired impact. The breakdown of students is as follows: Table 1. Class enrollment. (ii) Cross-Disciplinary Research The family of Heusler alloys possesses a wealth of interesting physics and potentially applied physical properties. They range from high spin-polarizations to magnetocaloric effects, and have therefore attracted the interests of researchers across disciplines. The current research on pulsed laser deposited Co2MnSb thin films has facilitated a joint effort on incorporating Heusler alloy films into multiferroic devices; this project combined the efforts of our program at LSU Physics with the electrical engineering group (V. G. Harris) at Northeastern University. In addition, this research has spurred collaborative efforts with LSU Chemistry and the Naval Research Laboratory.