New Magnetic Structure Discovered

Highlight Date: 
01/21/2014
Display Section: 
Broad Audience Highlights
Article Title: 
Coexistence of Half-Metallic Itinerant Ferromagnetism with Local-Moment Antiferromagnetism in Ba<sub>0.60</sub>K<sub>0.40</sub>Mn<sub>2</sub>As<sub>2</sub>
Author(s): 
A. Pandey, B. G. Ueland, S. Yeninas, A. Kreyssig, A. Sapkota, Y. Zhao, J. S. Helton, J. W. Lynn, R. J. McQueeney, Y. Furukawa, A. I. Goldman, and D. C. Johnston
Article Link: 
Journal Name: 
Physical Review Letters
Volume: 
111
Year: 
2013
Page Number(s): 
047001
Highlight Text: 

A new metallic material — based on the substitution of manganese for iron in an iron–arsenide superconductor — has been discovered in which the microscopic magnets of the electron current carriers provided by the potassium atoms all line up in the same direction at low temperatures whereas the neighboring microscopic magnets of the manganese atoms line up in opposite directions to each other.This material, Ba0.6K0.4Mn2As2, thus exhibits a novel magnetic behavior with ferromagnetic and antiferromagnetic behavior coexisting.  Interestingly, the ordered moments in the two magnetic substructures are aligned perpendicular to each other.Understanding what causes this unique magnetic structure may help researchers to understand the mechanism of high temperature superconductivity and to design materials for the new field of spintronics, where electron magnets are used in electronic devices for information processing rather than their charge.

Too Crowded to Exit!

Highlight Date: 
01/17/2014
Display Section: 
Division of Chemical and Biological Sciences
Broad Audience Highlights
Article Title: 
Alkyl Group versus Hydrogen Atom Transfer from Metal Alkyls to Macrocyclic Rhodium Complexes
Author(s): 
J. M. Carraher and A. Bakac
Article Link: 
Journal Name: 
Chemical Communications
Volume: 
49
Year: 
2013
Page Number(s): 
6099-6101
Highlight Text: 

Crowding controls whether carbon chains or a hydrogen atom will transfer from transition metal molecular complexes to acceptor molecules.To gain this new insight into the factors governing the onset of hydrogen abstraction from metal alkyls, researchers carefully designed experiments involving series of cobalt and chromium alkyls.  The results show that when the alkyl chain is only one carbon long, the alkyl group will transfer to a rhodium acceptor molecule.  But, if the chain is made up of two or more carbons, crowding makes it hard for the alkyl group to transfer.  In these cases the reaction finds another pathway, one in which a single hydrogen atom, rather than the entire alkyl group, is transferred.  The transfer of hydrogen and carbon chains from transition metal molecular complexes to an acceptor molecule is involved in many catalytic reactions of industrial and biological significance.  These results provide key fundamental information about these processes. 

Contacts:                                                                    For Release: Feb. 3, 2014
Iver Anderson, senior metallurgist, (515) 294-5816
Laura Millsaps, Public Affairs, (515) 294-3474

 

ImageIver Anderson, senior metallurgist at the U.S. Department of Energy’s Ames Laboratory and adjunct professor in the Materials Science and Engineering Department at Iowa State University, has been chosen as a recipient of the 2014 Application to Practice Award by TMS, the Minerals, Metals and Materials Society.

The award is given to a person who has demonstrated outstanding achievement in transferring research in metallurgy and materials into commercial production and practical use as a representative of an industrial, academic, governmental, or technical organization.

Ames Laboratory Interim Director Tom Lograsso said the lab was fortunate to have Anderson driving the commercialization of materials developed there, calling him “a remarkable scientist and a practical metallurgist.”

“Iver has a natural talent for devising solutions to materials problems, the ingenuity to develop new materials, the ability to address both the scientific and technical challenges, and the persistence to put those new materials on a fast track to commercial use,” said Lograsso.

Anderson will accept the award at the 2014 TMS-AIME awards ceremony held Feb. 18 in San Diego, Calif.

Anderson attributed his success to a philosophy that goes back to his undergraduate days at Michigan Technological University.

“My background is metallurgical engineering, and the whole idea behind the discipline is what you do in science should have a reason. It should solve a problem. It’s that aspect of what I do that is so exciting to me. These problems are often difficult ones, so if you figure out a way to solve it, you feel you’ve really contributed something. It makes science relevant to our lives; it’s why I do science.”

Anderson has a Ph.D. in metallurgical engineering from University of Wisconsin (1982); he worked at the U.S. Naval Research Laboratory from 1982-1987, and at the Ames Laboratory since 1987.

His research is on powder metallurgy and rapid solidification, involving high-pressure gas atomization of fine metal powders and highly controlled powder processing of rare earth compounds, magnetic materials, structural components, lightweight and porous materials, and joining problems including lead-free solders and ceramic joining. 

Anderson is a fellow of both the American Powder Metallurgy Institute and ASM International.  Currently, he is serving on the Board of Trustees of ASM International.  Previous TMS awards are the 2008 Distinguished Scientist/Engineer Award (EMPM Division) and the 1996 TMS Distinguished Service Award.  Other honors include 1991 and 2010 Federal Laboratory Consortium Awards for Excellence in Technology Transfer, a 1991 R&D-100 Award, the 2001 Energy 100 Award, 2006 Iowa Inventor of the Year, 2008 Excellence in Research Award from the Materials Science and Engineering Department at Iowa State, and the 2010 Iowa State University Intellectual Property Award.  Recent recognition for his work is the 2013 D.R. Boylan Eminent Faculty Award for Research from Iowa State University.  He has over 170 publications and 36 patents. 

Ames Laboratory is a U.S. Department of Energy Office of Science national laboratory operated by Iowa State University. Ames Laboratory creates innovative materials, technologies and energy solutions. We use our expertise, unique capabilities and interdisciplinary collaborations to solve global problems.

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Synthesis of organolanthanide compounds for catalysis

We are developing new f element compounds as catalysts for a number of homogeneous and heterogeneous reactions as part of the Critical Materials Institute Energy HUB. Our ultimate goal is to discover new catalysts for important processes, such as hydrocarbon functionalization, carbon-nitrogen bond formation, oxygen-transfer, and hydrogenation. Students working on this project will learn about synthetic organolanthanide chemistry, homogeneous catalysis, heterogenous catalysis, and high throughput methods in chemistry.

Catalytic Hydrodeoxyation

We are developing organometallic compounds to act as catalysts for conversion of biomass and biorenewable materials. Generally, the compounds, materials, and catalysts used for conversion of reduced petroleum feedstocks are not appropriate for the highly oxygenated biologically-derived materials. Instead, water soluble, moderately reduced metal centers are needed for alcohol, ester, ether and carboxylate activation.

Mass spectrometric imaging of plant metabolites

We are developing mass spectrometric imaging technique to analyze plant metabolites in single cell level. With this new technique, we can reveal unprecedented details of plant metabolism.

We are using top-notch instrumentation for this project, matrix-assisted laser desorption ionization (MALDI)-linear ion trap-orbitrap mass spectrometer. By reducing the laser beam size down to 10um size, we
can probe molecules present in very narrow area, and acquire high-resolution mass spectra for over thousands of x and y positions.

Seven Ames Laboratory scientists have been recognized for their outstanding scientific achievement and service to professional organizations.

Three scientists have been named 2014 Fellows of the American Physical Society. The APS Fellow award recognizes exceptional contributions the field of physics through research, application, service or education.

Adam Kaminski for “angle-resolved photoemission spectroscopy studies of unconventional superconductors.”

Klaus Schmidt-Rohr for “inventing and improving advanced solid-state NMR techniques that provide important new information about polymers, such as the Nafion used in fuel cells, those which occur naturally in plants and soils, and those which form nanocomposites in bone.”

Makariy Tanatar for “studies of the superconducting and normal states of unconventional superconductors using directional charge and heat transport measurements.”

Two Ames Lab scientists were named 2014 APS Outstanding Referees. The award recognizes scientists for their exceptional quality, number and timeliness of their work assessing manuscripts for publication in APS scientific journals.

Andreas Kressig and Pat Thiel are among the class of 2014 Outstanding Referees.

Earlier in the year, the APS announced Paul Canfield as the winner of the 2014 David Adler Lectureship Award in the Field of Materials Physics. The award recognizes outstanding materials physicists who have made noted contributions through their research, review articles and lecturing.

 

The World Association of Theoretical and Computational Chemists has named Ames Lab scientist Mark Gordon the 2014 Schrodinger Metal winner. The WATOC awards the Schrodinger medal each year to one outstanding theoretical and computational chemist.

 

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Kaminski
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Schmidt-Rohr
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Tanatar
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Kressig
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Thiel
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Canfield
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Gordon

Contacts:                                                                    For Release: Jan. 16, 2014
Jigang Wang, Ames Laboratory, 515-294-5630
Breehan Gerleman Lucchesi, Public Affairs, 515-294-9750

Scientists at the U.S. Department of Energy's Ames Laboratory have demonstrated broadband terahertz (THz) wave generation using metamaterials. The discovery may help develop noninvasive imaging and sensing, and make possible THz-speed information communication, processing and storage. The results appeared in the Jan. 8 issue of Nature Communications.

Terahertz electromagnetic waves occupy a middle ground between electronics waves, like microwave and radio waves, and photonics waves, such as infrared and UV waves. Potentially, THz waves may accelerate telecom technologies and break new ground in understanding the fundamental properties of photonics. Challenges related to efficiently generating and detecting THz waves has primarily limited their use.

Traditional methods seek to either compress oscillating waves from the electronic range or stretch waves from the optical range. But when compressing waves, the THz frequency becomes too high to be generated and detected by conventional electronic devices. So, this approach normally requires either a large-scale electron accelerator facility or highly electrically-biased photoconductive antennas that produce only a narrow range of waves.

To stretch optical waves, most techniques include mixing two laser frequencies inside an inorganic or organic crystal. However, the natural properties of these crystals result in low efficiency.

So, to address these challenges, the Ames Laboratory team looked outside natural materials for a possible solution. They used man-made materials called metamaterials, which exhibit optical and magnetic properties not found in nature.

Costas Soukoulis, an Ames Laboratory physicist and expert in designing metamaterials, along with collaborators at Karlsruhe

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A THz spectrometer driven by femtosecond laser pulses was used to demonstrate THz emission from a split-ring resonator metamaterial
of single nanometer thickness.

Institute of Technology in Germany, created a metamaterial made up of a special type of meta-atom called split-ring resonators. Split-ring resonators, because of their u-shaped design, display a strong magnetic response to any desired frequency waves in the THz to infrared spectrum.

Image A team led by Ames Laboratory physicists demonstrated broadband, gapless terahertz emission (red line) from split-ring resonator metamaterials (background) in the telecomm wavelength. The THz emission spectra exhibit significant enhancement at magnetic-dipole resonance of the metamaterials emitter (shown in inset image). This approach has potential to generate gapless spectrum covering the entire THz band, which is key to developing practical THz technologies and to exploring fundamental understanding of optics.

Ames Laboratory physicist Jigang Wang, who specializes in ultra-fast laser spectroscopy, designed the femto-second laser experiment to demonstrate THz emission from the metamaterial of a single nanometer thickness.

“The combination of ultra-short laser pulses with the unique and unusual  properties of the metamaterial generates efficient and broadband THz waves from emitters of significantly reduced thickness,” says Wang, who is also an associate professor of Physics and Astronomy at Iowa State University.

The team demonstrated their technique using the wavelength used by telecommunications (1.5 microns), but Wang says that the THz generation can be tailored simply by tuning the size of the meta-atoms in the metamaterial.

“In principle, we can expand this technique to cover the entire THz range,” said Soukoulis, who is also a Distinguished Professor of physics and astronomy at Iowa State University.

What’s more, the team’s metamaterial THz emitter measured only 40 nanometers and performed as well as traditional emitters that are thousands of times thicker.

“Our approach provides a potential solution to bridge the ‘THz technology gap’ by solving the four key challenges in the THz emitter technology:  efficiency; broadband spectrum; compact size; and tunability,” said Wang.

Soukoulis, Wang, Liang Luo and Thomas Koschny's work at Ames Laboratory was supported by the U.S. Department of Energy's Office of Science. Wang's work is partially supported by Ames Laboratory’s Laboratory Directed Research and Development (LDRD) funding.

DOE’s Office of Science is the single largest supporter of basic research in the physical sciences in the United States, and is working to address some of the most pressing challenges of our time. For more information, please visit the Office of Science website at science.energy.gov/.

Ames Laboratory is a U.S. Department of Energy Office of Science national laboratory operated by Iowa State University. Ames Laboratory creates innovative materials, technologies and energy solutions. We use our expertise, unique capabilities and interdisciplinary collaborations to solve global problems.


VFP Research Projects

Ames Lab provides hands-on research opportunities in materials science in the following research areas:

CCI Technical Projects

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