Preparation, Magnetism, and Applications of Thin Films of the Organic Semiconductor V[TCNE]$_{x\sim 2}$

Different aspects of the room-temperature (T$_{c}>$350K) molecular magnet vanadium tetracyanoethylene (V[TCNE]$_{x\sim 2})$ remain only partially understood, including its intra- and inter-molecular bonding and spin distribution, degradation mechanisms, and mesoscopic magnetic and chemical order. Previous studies have shown that control of the local order, structure, spin, and chemical composition determines the magnetic state achieved and its charge transport and dynamic properties$^{1}$. In this study, we focus on thin films ($\sim $0.05-0.5 $\mu $m) prepared by CVD$^{2,3}$ (room temperature conductivity 10$^{-4}$-10$^{-3 }$S/cm). Soft x-ray absorption and Magnetic Circular Dichroism (MCD) spectra of the atomic edges are presented, together with XPS, SQUID magnetometry, and EPR spectroscopy. The knowledge gained enables successful demonstration of spin valve devices and photoinduced magnetism in this molecule-based magnetic semiconductor. 1. Pokhodnya, et al, PRB \textbf{63}, 174408 (2001) 2. Pokhodnya, et al, Adv. Mater. \textbf{12}, 410 (2000) 3. Shima, et al, MRS Proc. \textbf{871E}, I7.3 (2005) Supported by DOE grants {\#}DE-FG02-86ER45271, DE-FG02- 01ER45931, DE-AC03-76SF00098, and AFOSR grant {\#}F49620-03-1-0175. NSF-DMR grant {\#}0114098 and Dr. Lisa Hommel are acknowledged for XPS studies.