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Current Research
The research in my group is broadly focused on quantum and spin phenomena in nanomagnetic structures. Newly discovered nanoscale structures with exceptional properties represent one of the most dynamic and exciting areas in science and technology. The emergence of nanoscience and nanotechnology has brought to the fore the concepts of deliberate fabrication of composite structures by either “bottom-up” or “top-down” methods. The top-down method has worked well for decades in the miniaturization process but is reaching its limits. The bottom-up method relies on the principle of self-assembly or self-organization, and has great potential for creating nanoscale systems that possess completely new properties. Future research likely will involve combined top-down and bottom-up approaches. Many new phenomena and devices are under study with these ideas including giant magnetoresistance sensors, high-density data storage and memory, spintronics, and exchange-coupled nanomagnets. Our research is focused on several of these areas.
Students and postdocs in my group learn and do research in a broad range of topics in materials, magnetism and nanoscience. Synthetic methods include sputtering, nanocluster deposition, self-assembly, electrodeposition, focused-ion-beam milling and others. Structural characterization methods include x-ray diffraction and transmission electron microscopy. Physical property measurements include SQUID, AGFM, and VSM magnetometry, electrical resistance, Hall effect, magnetoresistance, and Moessbauer effect. Our group is well known for fabrication of novel nanomagnetic structures and for strong integration of experiment with theory. Many of the topics under investigation in our group are basic science but related to nanomagnetic structures for future information technologies. These include: (i) High-anisotropy magnetic nanocluster-assembled films; (ii) Nanotube magnetism; (iii) Spin-logic nanostructures; (iv) Exchange-coupled nanocomposites; (v) Magnetic semiconductors for spintronics; and (vi) Quantum entanglement in nanodots.
Recent Publications
J.P. Liu, E. Fullerton, O. Gutfleisch, D.J. Sellmyer, Eds., Nanoscale Magnetic Materials and Applications, (Springer, Berlin, 2009).
T. Mukherjee, S. Sahoo, R. Skomski, D.J. Sellmyer, and Ch. Binek, “Magnetocaloric Properties of Co/Cr Superlattices,” Phys. Rev. B 79, 144406 (1-9) (2009).
Lanping Yue, Zhen Li, Roger Kirby, and David Sellmyer, “MFM Studies of Interlayer Exchange Coupling in Co/Ru/Co Films: Effect of Ru Layer Thickness,” Ultramicroscopy 109, 1040-1043 (2009).
R. Skomski, G.C. Hadjipanayis, and D.J. Sellmyer, “Graded Permanent Magnets,” J. Appl. Phys. 105, 07A733 (2009).
T.A. George, R. Skomski, and D.J. Sellmyer, “Magnetic Correlations in Nanocomposite FePt:Au and FePt:C Films,” J. Appl. Phys. 105, 07B736 (2009).
Xiaohui Wei, Ralph Skomski, B. Balamurugan, Z.G. Sun, Stephen Ducharme, and D.J. Sellmyer, “Magnetism of TiO and TiO2 Nanoclusters,” J. Appl. Phys. 105, 07C517 (2009).
N.G. Akdogan, G.C. Hadjipanayis, and D.J. Sellmyer, “Anisotropic Sm2(Co,Fe)17 Nanoparticles Produced by Surfactant Assisted Ball Milling,” J. Appl. Phys. 105, 07A710 (2009).
X. Rui, J.E. Shield, Z. Sun, R. Skomski, Y. Xu, D.J. Sellmyer, M.J. Kramer and Y.Q. Wu, “Intra-Cluster Exchange-Coupled High-Performance Permanent Magnets,” J. Magn. Magn. Mater. 320, 2576-2583 (2008).
X.-H. Wei, R. Skomski, Z.-G. Sun, and D. J. Sellmyer, "Proteresis in Co:CoO Core-Shell Nanoclusters," J. Appl. Phys. 103, 07D514 (1-3) (2008).
R. Skomski, X. Wei, and D. J. Sellmyer, "Band-Structure and Correlation Effects in the Co(111) Planes of CoO," J. Appl. Phys. 103, 07C908 (1-3) (2008).
A. K. Pradhan, R. Bah, R. B. Konda, R. Mundie, H. Mustafa, O. Bamiduro, R. R. Rakhimov, Xiaohui Wei, and D.J. Sellmyer, “Synthesis and Magnetic Characterizations of Manganite-Based Composite Nanoparticles for Biomedical Applications,” J. Appl. Phys. 103, 07F704 (1-3) (2008).
R. Skomski, T. A. George, D.J. Sellmyer, “Nucleation and Wall Motion in Graded Media,” J. Appl. Phys. 103, 07F531 (1-3) (2008).
R. Skomski, J. P. Liu, C. B. Rong, and D.J. Sellmyer, “Hysteresis of Ultrasmall Fe-Pt Particles,” J. Appl. Phys. 103, 07E139 (1-3) (2008).
Chaehyun Kim, Thomas Loedding, Seongjin Jang, Hao Zeng, Zhen Li, Yucheng Sui, and David J. Sellmyer, “FePt Nanodot Arrays with Perpendicular Easy Axis, Large Coercivity, and Extremely High Density,” Appl. Phys. Lett. 91, 172508 (1-3) (2007).
J. Zhang, R. Skomski, D.J. Sellmyer, “Structure and Magnetism of V-Doped SnO2 Thin Films: Effect of Substrate,” J. Phys. Condens. Matter 19, 256204 (1-6) (2007).
J. Zhang, R. Skomski, Y.F. Lu, and D.J. Sellmyer, “Temperature-Dependent Orbital-Moment Anisotropy in Dilute Magnetic Oxides,” Phys. Rev. B 75, 214417 (2007).
Ralph Skomski and D.J. Sellmyer, “Magnetic Impurities in Magic-Number Clusters,” J. Appl. Phys. 101, 09G524 (2007).
Y.F. Xu, M.L. Yan, and D.J. Sellmyer, “FePt Nanocluster Films for High-Density Magnetic Recording,” Review Article, J. Nanosci. Nanotech. 7, 206-224 (2007).
D.J. Sellmyer, Y.F. Xu, Y.C. Sui, and R. Skomski, “Novel Nanoparticulate Magnetic Materials and Structures,” in Handbook of Magnetism and Advanced Magnetic Materials, Eds. H. Kronmüller and S. Parkin, Vol. 4, Novel Materials, Eds. M. Coey and A. Inoue (J. Wiley and Sons, Ltd, UK, 2007), pp. 2177-2190.
Y. Liu, D.J. Sellmyer, D. Shindo, Eds., Handbook of Advanced Magnetic Materials, Vol. 1: Nanostructural Effects; Vol. 2: Characterization and Simulation; Vol. 3: Fabrication and Processing; Vol. 4: Properties and Applications (Springer, Berlin, 2006).
David Sellmyer and Ralph Skomski, Eds., Advanced Magnetic Nanostructures (Springer, Berlin, 2006).
Recent Postdoctoral and Researchers, Graduates
- Dr. Y. Qiang, Associate Professor, University of Idaha
- Dr. M. Yan, Western Digital Corp.
- Dr. M. Chipara, Assistant Professor, University of Texas-Pan American
- Dr. J. Zhou, Western Digital Corp.
- Dr. Y. Sui, Northern Natural Gas Co.
- Dr. J. Zhang, Ohio State University
- Dr. K. Sorge, Assistant Professor, Florida Atlantic University
- Dr. H. Zeng, Associate Professor, University at Buffalo, SUNY
- Dr. M. Daniil, Naval Research Laboratory
