Research - IRG1

Nanoscale Spin-Polarized Matter by Design

The goal of this IRG is to advance our understanding of exciting topics relevant to several grand challenges in nanomagnetism and nanoscience. These include: 1) Quantum understanding of spin-polarized matter at the 1-10 nm scale, which bridges the gap between molecular and macroscopic levels 2) Complexity in fabrication and integration of top-down and self-assembled nanomagnetic structures; 3) Ultra-high-density information storage; 4) Nanomagnetic basis for magnetologic, spintronic, and spin qubit devices; 5) Ultra-strong permanent magnets; and 6) Ultra-small biomagnetic and other sensors. The length scale involved is one where new quantum approaches and simulations are needed, and where novel “superatomic” species may lead to new phenomena and magnetic properties. Complex surfaces and interfaces are of extreme importance and the synthesis and fabrication of the nanostructures are equally critical as the theoretical and characterization portions of the research. In addition to the basic-science aspects of the work, there are opportunities for major technological implications in information storage and processing, energy production and conservation, defense, and medicine.
This IRG brings a powerful combination of theoretical and experimental expertise to bear on several of the above-mentioned challenges.


IRG 1 Research Areas:



A. Novel Structures and Quantum Phenomena in Nanomagnets:

This research theme involves the design, fabrication and study of special nanostructures that provide atomic scale understanding of the exchange interaction and magnetic anisotropy. In addition the work is directed towards several magnetic composite structures and devices with high potential for emerging applications.

Topics:

  • Novel Structures and Magnetism in Nanoclusters
  • Spin-Polarized Scanning Tunneling Microscopy of Magnetic Nanostructures
  • Spin Clusters and Kondo Effect in a Ferromagnet
  • Topological Excitations in Nanomagnets

B. Low-Dimensional Structures and Applications:

This research theme involves the design, fabrication and study of special nanostructures that provide atomic scale understanding of the exchange interaction and magnetic anisotropy. In addition the work is directed towards several magnetic composite structures and devices with high potential for emerging applications.
Progress in these objectives is essential to determine the ultimate physical limits for magnetism-based technologies including data storage, magnetologic and spintronics. This endeavor is including identifying conditions for the stabilization of magnetization in particles of extremely reduced magnetic volume at room temperature, determining the extent to which exchange-coupled magnetic nanostructures can be fabricated with controlled properties and behaviors, and understanding and controlling the fast and complex reversal processes implicit in nanoscale structures and devices.

Topics:

  • Domain Walls and Domain Interactions in Artificial Antiferromagnets
  • Control of Surface Magnetism and Anisotropy
  • High-Sensitivity Detector for Molecular Sensing Using Magnetic Particles
  • Assembly and Alignment of Nano-Objects for Advanced Magnetic Materials


IRG 1 Highlights:


» Nano Letters 2014
- X. Wei, R. Zhou, W. Lefebvre, K. He, D. Le Roy, R. Skomski, X. Li, J. E. Shield, M. J. Kramer, S. Chen, X. C. Zeng, and D. J. Sellmyer, "Structural and Magnetic Evolution of Bimetallic MnAu Clusters Driven by Asymmetric Atomic Migration," Nano Lett.  14, 1362−1368 (2014).
- C. Phatak, Y. Liu, E. B. Gulsoy, D. Schmidt, E. Schubert, and A. Petford-Long, “Visualization of the magnetic structure of sculpted three-dimensional cobalt nanospirals,” Nano Lett. 14, 759-764 (2014).

» Advanced Materials 2013

B. Balasubramanian, B. Das, R. Skomski, W. Y. Zhang, and D. J. Sellmyer, “Novel nanostructured
rare-earth-free magnetic materials with high energy products,” Adv. Mater. 25, 6090-6093 (2013).

» Published Book 2012
Simple Models of Magnetism” by Ralph Skomski (Oxford University Press) (June 2012).

» Magnetic Technology International - Showcase 2012
D. J. Sellmyer and B. Balasubramanian,"Assembly of nano-objects," Magnetic Technology International - Showcase 2012, pp. 40-44 (Nov. 2012). Image featured on cover page.

» Nano Letters 2011
B. Balasubramanian, R. Skomski, X. Li, S. R. Valloppilly, J. E. Shield, G. C. Hadjipanayis, and D. J. Sellmyer, “Cluster Synthesis and Direct Ordering of Rare-Earth Transition-Metal Nanomagnets,” Nano Lett. 11 (4), 1747-52 (2011).

» ACS Nano 2011
R. Zhou, X. Wei, K. He, J. E. Shield, D. J. Sellmyer, and X. C. Zeng, “Theoretical and Experimental Characterization of Structures of MnAu Nanoclusters in the Size Range of 1-3 nm,” ACS Nano 5 (12), 9966-76 (2011).

» Journal of Physics: Condensed Matter 2011 - Featured at IOP labtalk.
P. Kharel and D. J. SellmyerAnomalous Hall Effect and Electron Transport in Ferromagnetic MnBi Films,” Phys.: Condens. Matter 23, 426001 (2011).

» ACS Nano 2010
B. Balasubramanian, K. L. Kraemer, N. A. Reding, R. Skomski, S. Ducharme, and D. J. Sellmyer, “Synthesis of Monodisperse TiO2-Paraffin Core-Shell Nanoparticles for Improved Dielectric Properties,” ACS Nano 4 (4), 1893-1900 (2010).

» Journal of Physics: Condensed Matter - Top 20 most cited Topical Review articles
(20th anniversary JPCM)
(Nov. 2009)
R. Skomski, “Nanomagnetics” J. Phys.: Condens. Matter 15, R841-896 (2003).

» International Collaboration between United Kingdom, Germany, Austria, and USA:
J. Honolka, T. Y. Lee, K. Kuhnke, A. Enders, R. Skomski, S. Bornemann, S. Mankovsky, J. Minar, J. Staunton, H. Ebert, M. Hessler, K. Fauth, G. Schütz, A. Buchsbaum, M. Schmidt, P. Varga, and K. Kern, “Magnetism of FePt Surface Alloys,” Phys. Rev. Lett. 102, 067207 (2009).

IRG1

 


IRG 1 Researchers

David Sellmyer (coordinator) - Nanofabrication, clusters (SQUID etc.)

Axel Enders - Nanofabrication, self-assembled nanostructures (STM)

Roger Kirby - Laser patterning (MO, Fast Dynamics)

Sy-Hwang Liou - Nanofabrication (SPM and MTM)

Renat Sabirianov - First principles calculations and micromagnetic modeling

Eva Schubert - Nanofabrication, chiral materials

Jeff Shield - Clusters and mechanical methods (TEM etc.)

Ralph Skomski - Theory of magnetic nanostructures

Xiao-Cheng Zeng - Density-functional theory (DFT) calculations