| AVS 56th International Symposium & Exhibition | |
| Magnetic Interfaces and Nanostructures | Friday Sessions |
| Session MI-FrM |
| Session: | Molecular/Organic Based Magnetism |
| Presenter: | A.J. Epstein, The Ohio State University |
| Correspondent: | Click to Email |
In recent years a broad range of magnetic and magnetotransport phenomena have been reported for organic semiconductors. Unpaired spins in the p orbitals of organic systems have been shown to yield new physics and be the basis of potential new technologies of broad interest. Organic-based magnets with magnetic ordering temperatures from a few K [1] to > 400 K [2] have been successfully synthesized. In addition, new magnetic phenomena have been discovered including fractal magnetism, photonically controlled magnetism, nanoscale magnetic bubbles, and fully spin polarized magnetic semiconductors[3]. Further, magnetotransport (MR) in magnetic and nonmagnetic organic semiconductors has revealed a host of heretofore unknown spin-dependent phenomena, including 20% change in resistance at room temperature for application of as little as 100 Oe to nonmagnetic organic semiconductors. The room temperature magnetic semiconductors V[TCNE]x~2, (TCNE ≡ tetracyanoethylene) [2,3] has many new properties such as fully spin polarized energy bands and magnetism from 0 to 400 K and photonic response. The analogue Fe[TCNE]x forms monolayer thick spin layers that produce ‘spin bubbles’ upon application of a critical field.
These advances in science have prompted interest in the possibility of technologies based on these new materials. These new potential technologies will be discussed with emphasis on organic-based spintronics including tunneling magnetoresistance (TMR) and giant magnetoresistance (GMR) devices and also use of these materials as sensors in the emerging THz range.
This work was supported in part by NSF, DOE, AFOSR, and OSU Inst. for Mater. Res.
[1] S. Chittipeddi, K. Cromack, J.S. Miller, and A.J. Epstein, “Ferromagnetism in Molecular DecamethylferroceniumTetracyanoethenide (DMeFc)(TCNE)”, Phys. Rev. Lett. 58, 2695 (1987).
[2] J.M. Manriquez, G.T. Yee, R.S. McLean, A.J. Epstein, and J.S. Miller,“A Room Temperature Molecular/Organic-Based Magnet”, Science 252, 1415 (1991).
[3] A.J. Epstein, “Organic-based Magnets: Opportunities in Photoinduced Magnetism, Spintronics, Fractal Magnetism, and Beyond”, Mater. Res. Soc. Bull. 28, 492-499 (2003).
[4 V.N. Prigodin, J.D. Bergeson, D.M. Lincoln, and A.J. Epstein, “Anomalous Room Temperature Magnetoresistance in Organic Semiconductors”, Synth. Met. 156, 757 (2006).
[5] T. Francis, O¨. Mermer, G. Veeraraghavan, and M. Wohlgenannt, “Large Magnetoresistance at RoomTemp. in Semiconducting Polymer Sandwich Devices”,New J. Phys. 6, 185 (2004).