This discovery raises hopes for even smaller and faster gadgets that could result from magnetic data storage in a semiconductor material, which could then quickly process the data through built-in logic circuits controlled by electric fields.
Magnetic data storage is currently utilized with great success in consumer products such as computer hard drives and MP3 players. But these storage devices are based on metallic materials. These conventional hard drives can only hold data; they have to send the data to a semiconductor-based device to process the data, slowing down performance.
In a new paper,* researchers from NIST, Korea University and the University of Notre Dame have confirmed theorists’ hopes that thin magnetic layers of semiconductor material could exhibit a prized property known as antiferromagnetic coupling—in which one layer spontaneously aligns its magnetic pole in the opposite direction as the next magnetic layer. The discovery of antiferromagnetic coupling in metals was the basis of the 2007 Nobel Prize in Physics, but it is only recently that it has become conceivable for semiconductor materials. Semiconductors with magnetic properties would not only be able to process data, but also store it.
The most widely studied magnetic semiconductor is gallium arsenide (GaAs) with magnetic atoms (manganese) taking the place of some of the gallium atoms. Theorists had predicted that by creating thin films of this material separated by a nonmagnetic material of just the right thickness and electrical properties, one could engineer antiferromagnetic (AF) coupling. With magnetic fields, one could then switch the magnetization of one of the layers back and forth to create “spintronic” logic circuits, ones that operate not only under the usual control of electric fields but also the influence of magnetic fields (manipulating a property known as spin, which could be imagined as tiny internal bar magnets in particles such as electrons).
The team, working at the NIST Center for Neutron Research, studied these multilayer stacks using a technique known as polarized neutron reflectometry. In this technique, a beam of neutrons is bounced off the stacks. Since neutrons are magnetic, and are able to easily penetrate through the entire stack, the reflected neutrons provide information about the magnetic properties of the individual layers. At low temperatures and small magnetic fields, the polarized neutron data unambiguously confirm the existence of an antiparallel magnetic alignment of neighboring layers. When the magnetic field was increased, the neutron data indicated a parallel alignment of all layers. These results demonstrate that AF coupling is achievable in GaMnAs-based multilayers, a seminal property that now opens up a multitude of device possibilities for this novel material. While the phenomenon only occurs at very cold temperatures in the material (about 30 K), the researchers believe these results will help inform theorists who could then better understand how to create room-temperature devices with the same magnetic properties.
* J.-H. Chung, S.J. Chung, S. Lee, B.J. Kirby, J.A. Borchers, Y.J. Cho, X.Liu and J.K. Furdyna, Carrier-mediated antiferromagnetic interlayer exchange coupling in diluted magnetic semiconductor multilayers Ga1-xMnxAs/GaAs:Be. Physical Review Letters, to be published.
Ben Stein | Newswise Science News
Significantly more productivity in USP lasers
06.12.2016 | Fraunhofer-Institut für Lasertechnik ILT
Shape matters when light meets atom
05.12.2016 | Centre for Quantum Technologies at the National University of Singapore
In recent years, lasers with ultrashort pulses (USP) down to the femtosecond range have become established on an industrial scale. They could advance some applications with the much-lauded “cold ablation” – if that meant they would then achieve more throughput. A new generation of process engineering that will address this issue in particular will be discussed at the “4th UKP Workshop – Ultrafast Laser Technology” in April 2017.
Even back in the 1990s, scientists were comparing materials processing with nanosecond, picosecond and femtosesecond pulses. The result was surprising:...
Have you ever wondered how you see the world? Vision is about photons of light, which are packets of energy, interacting with the atoms or molecules in what...
A multi-institutional research collaboration has created a novel approach for fabricating three-dimensional micro-optics through the shape-defined formation of porous silicon (PSi), with broad impacts in integrated optoelectronics, imaging, and photovoltaics.
Working with colleagues at Stanford and The Dow Chemical Company, researchers at the University of Illinois at Urbana-Champaign fabricated 3-D birefringent...
In experiments with magnetic atoms conducted at extremely low temperatures, scientists have demonstrated a unique phase of matter: The atoms form a new type of quantum liquid or quantum droplet state. These so called quantum droplets may preserve their form in absence of external confinement because of quantum effects. The joint team of experimental physicists from Innsbruck and theoretical physicists from Hannover report on their findings in the journal Physical Review X.
“Our Quantum droplets are in the gas phase but they still drop like a rock,” explains experimental physicist Francesca Ferlaino when talking about the...
The Max Planck Institute for Physics (MPP) is opening up a new research field. A workshop from November 21 - 22, 2016 will mark the start of activities for an innovative axion experiment. Axions are still only purely hypothetical particles. Their detection could solve two fundamental problems in particle physics: What dark matter consists of and why it has not yet been possible to directly observe a CP violation for the strong interaction.
The “MADMAX” project is the MPP’s commitment to axion research. Axions are so far only a theoretical prediction and are difficult to detect: on the one hand,...
16.11.2016 | Event News
01.11.2016 | Event News
14.10.2016 | Event News
07.12.2016 | Health and Medicine
07.12.2016 | Life Sciences
07.12.2016 | Health and Medicine