Highlights of research in the magnetic materials group

A Colossal Magnetic Effect under Pressure

June 12, 2009

“Giant” and “colossal” aren’t the words that come to mind when thinking about MP3 players or laptops. But we can store and access ever-increasing amounts of data on ever-smaller devices because of giant magnetoresistance. Now researchers using the U.S. Department of Energy’s Advanced Photon Source at Argonne National Laboratory are delving into the forces colossal magnetoresistance, which is up to a thousand times more powerful than GMR and could trigger another revolution in computing technology

A New Spin on Inducing Chirality in Pre-biological Molecules

October 23, 2008

Researchers using an x-ray beamline at the U.S. Department of Energy’s Advanced Photon Source demonstrated that a previously unconsidered mechanism can play a role in chiral-selective chemistry: namely low-energy spin-polarized secondary electrons, produced by irradiation of a magnetic substrate.

Different Roads Toward Quantum Criticality

October 17, 2007

The study of magnetic phase diagrams is essential to understanding the organizing principles of correlated electrons, as well as understanding the way in which physical parameters determine material properties.

Logic Tells Us that Appearances May Be Deceptive

September 24, 2007

There is a worldwide effort to utilize magnetic rings for the development of novel computer-memory applications, such as magnetic random-access memories. Researchers using the Advanced Photon Source and Center for Nanoscale Materials at Argonne reveal, in the cover story of the 24 September 2007 issue of Applied Physics Letters, new insights into the behavior of multilayer ring structures for memories.

Giant Magnetocaloric Materials Could Have Large Impact on the Environment

June 15, 2007

Amid the growing awareness of climate change as a concern in need of solutions, research at the Argonne Advanced Photon Source may help reduce the levels of environmentally damaging hydrofluorocarbons in our atmosphere.

At the Boundary between Superconducting and Magnetic Oxides

April 12, 2006

The transistor, which shaped so much of our modern technology and economics, grew out of scientists’ desire to gain a greater understanding of the interfaces between different materials. In the same way, today’s materials scientists seek to expand our understanding of complex oxides by creating new states at the interface of two materials.

Defect-Driven Magnetism in Mn-doped GaN

December 12, 2005

Semiconductors doped with magnetic elements are candidates as room-temperature magnetic semiconductors with potential use as new low-power-consumption electronics, non-volatile memories, and field-configurable logic devices. Research at the U.S. Department of Energy’s Advanced Photon Source is producing new and important information about Mn-doped GaN.

Nanoskins on Layered Manganites

July 20, 2005

Researchers from Argonne National Laboratory have successfully demonstrated that an insulating nanoskin (an ultrathin insulating, non-ferromagnetic tunnel barrier layer) in contact with a completely ferromagnetic metallic layer can be naturally created. Assembling a uniform layer five atoms thick (10 Å) and without defects is no mean feat. In their Nature Materials paper, the researchers note that situating a well-defined surface insulator atop a fully spin-polarized bulk demonstrates that two of the most demanding components of an ideal magnetic tunnel junction can self-assemble naturally.

Using High Pressure to Reveal Quantum Criticality in an Elemental Antiferromagnet

May 21, 2009

New research at the U.S. Department of Energy’s Advanced Photon Source is a milestone in the study of emergent magnetism and quantum criticality. It opens new possibilities for high-pressure studies of fundamental magnetism and technologically important correlated electron materials.

Increasing Magnetic Response of Ferromagnetic Semiconductors under High Pressure

February 16, 2009

Scientists using the U.S. Department of Energy's Advanced Photon Source have manipulated electron mobility and pinpointed the mechanism controlling the strength of magnetic interactions in europium oxide and, hence, the material's magnetic ordering temperature.

Oldest Known Magnets Secrets Revealed Under High Pressures

February 1, 2008

Researchers using two high-brightness x-ray beamlines at the Argonne Advanced Photon Source have uncovered new information about the coupling between magnetic and electrical properties of this venerable and highly useful material magnetite.

Orbital Reconstruction at a Complex Oxide Interface

October 15, 2007

A current problem of intense interest to the condensed matter physics community is the behavior of systems with strongly interacting electrons. Researchers using the Argonne Advanced Photon Source have gained important new insights into this phenomenon.

Getting to the Core of Luminesent Nanowires

June 18, 2007

Researchers using the Argonne Advanced Photon Source have determined what is responsible for the luminescence exhibited by one-dimensional nanostructures that have great potential for optoelectronic devices such as blue-light lasers for next-generation optical storage media.

Tailoring the Properties of Magnetic Nanostructures

May 23, 2007

Studies carried out at the Advanced Photon Source show that subtle variations in shape can tailor the properties of magnetic nanostructures that could be used for new high-speed electronic devices.

What's in the Cage Matters in Iron Antimonide Thermoelectric Materials

March 29, 2007

Thermoelectric materials such as iron antimonide have drawn intense interest because they offer a pollution-free source of electricity and a vibration free source of refrigeration. Research at the Advanced Photon Source examined how the magnetism of cage-filler lanthanides may influence the thermoelectric properties of these materials.

Into the Vortex: Dynamics in Nanoscale Materials

February 20, 2006

Micron and nanosized magnets are of great interest for their potential applications in new electronic devices, such as magnetic random access memories. Researchers from Argonne National Laboratory have made some surprising discoveries about the behavior of these materials that may lead to a greater understanding of complex materials on the nanoscale.