Michigan team tests radiation-resistant spintronic material, possibly enabling electronic devices that will work in harsh environments
A team of researchers from the University of Michigan and Western Michigan University is exploring new materials that could yield higher computational speeds and lower power consumption, even in harsh environments.
A laser pulse is split into two paths: circularly polarized pump (blue) and linearly polarized probe (red). The pump's path length is adjustable using a delay stage so that the relative arrival time between the pump and probe can be adjusted. After the probe is reflected from the sample surface, the light is passed through a Walloston Prism and sent to a balanced photo-diode bridge. This allows for very sensitive measurements of the Faraday rotation due to electron spin polarizations.
Credit: AIP Publishing
Most modern electronic circuitry relies on controlling electronic charge within a circuit, but this control can easily be disrupted in the presence of radiation, interrupting information processing. Electronics that use spin-based logic, or spintronics, may offer an alternative that is robust even in radiation-filled environments.
Making a radiation-resistant spintronic device requires a material relevant for spintronic applications that can maintain its spin-dependence after it has been irradiated. In a paper published in the journal Applied Physics Letters, from AIP Publishing, the Michigan research team presents their results using bulk Si-doped n-GaAs exposed to proton radiation.
How Does Spintronics Work?
Modern electronic devices use charges to transmit and store information, primarily based upon how many electrons are in one place or another. When a lot of them are at a given terminal, you can call that 'on.' If you have very few of them at the same terminal, you can call that 'off,' just like a light switch. This allows for binary logic depending on whether the terminal is 'on' or 'off.' Spintronics, at its simplest, uses the 'on/off' idea, but instead of counting the electrons, their spin is measured.
"You can think of the spin of an electron as a tiny bar magnet with an arrow painted on it. If the arrow points up, we call that 'spin-up.' If it points down, we call that 'spin-down.' By using light, electric, or magnetic fields, we can manipulate, and measure, the spin direction," said researcher Brennan Pursley, who is the first author of the new study.
While spintronics holds promise for faster and more efficient computation, researchers also want to know whether it would be useful in harsh environments. Currently, radioactivity is a major problem for electronic circuitry because it can scramble information and in the long term degrade electronic properties. For the short term effects, spintronics should be superior: radioactivity can change the quantity of charge in a circuit, but should not affect spin-polarized carriers.
Studying spintronic materials required that the research team combine two well established fields: the study of spin dynamics and the study of radiation damage. Both tool sets are quite robust and have been around for decades but combining the two required sifting through the wealth of radiation damage research. "That was the most difficult aspect," explains Pursley. "It was an entirely new field for us with a variety of established techniques and terminology to learn. The key was to tackle it like any new project: ask a lot of questions, find a few good books or papers, and follow the citations."
Technically, what the Michigan team did was to measure the spin properties of n-GaAs as a function of radiation fluence using time-resolved Kerr rotation and photoluminescence spectroscopy. Results show that the spin lifetime and g-factor of bulk n-GaAs is largely unaffected by proton irradiation making it a candidate for further study for radiation-resistant spintronic devices. The team plans to study other spintronic materials and prototype devices after irradiation since the hybrid field of irradiated spintronics is wide open with plenty of questions to tackle.
Long term, knowledge of radiation effects on spintronic devices will aid in their engineering. A practical implementation would be processing on a communications satellite where without the protection of Earth's atmosphere, electronics can be damaged by harsh solar radiation. The theoretically achievable computation speeds and low power consumption could be combined with compact designs and relatively light shielding. This could make communications systems faster, longer-lived and cheaper to implement.
The article, "Robustness of n-GaAs carrier spin properties to 5MeV proton radiation," is authored by Brennan Pursley, X. Song, R.O. Torres-Isea, E.A. Bokari, A. Kayani and V. Sih. It appears in the journal Applied Physics Letters on February 17, 2015 (DOI: 10.1063/1.4907286). After that date, it will be available at: http://scitation.
The authors of this paper are affiliated with the University of Michigan and Western Michigan University.
ABOUT THE JOURNAL
Applied Physics Letters features concise, rapid reports on significant new findings in applied physics. The journal covers new experimental and theoretical research on applications of physics phenomena related to all branches of science, engineering, and modern technology. See: http://apl.
Jason Socrates Bardi | EurekAlert!
Novel light sources made of 2D materials
28.10.2016 | Julius-Maximilians-Universität Würzburg
OU-led team discovers rare, newborn tri-star system using ALMA
27.10.2016 | University of Oklahoma
Physicists from the University of Würzburg have designed a light source that emits photon pairs. Two-photon sources are particularly well suited for tap-proof data encryption. The experiment's key ingredients: a semiconductor crystal and some sticky tape.
So-called monolayers are at the heart of the research activities. These "super materials" (as the prestigious science magazine "Nature" puts it) have been...
Ultrafast lasers have introduced new possibilities in engraving ultrafine structures, and scientists are now also investigating how to use them to etch microstructures into thin glass. There are possible applications in analytics (lab on a chip) and especially in electronics and the consumer sector, where great interest has been shown.
This new method was born of a surprising phenomenon: irradiating glass in a particular way with an ultrafast laser has the effect of making the glass up to a...
Terahertz excitation of selected crystal vibrations leads to an effective magnetic field that drives coherent spin motion
Controlling functional properties by light is one of the grand goals in modern condensed matter physics and materials science. A new study now demonstrates how...
Researchers from the Institute for Quantum Computing (IQC) at the University of Waterloo led the development of a new extensible wiring technique capable of controlling superconducting quantum bits, representing a significant step towards to the realization of a scalable quantum computer.
"The quantum socket is a wiring method that uses three-dimensional wires based on spring-loaded pins to address individual qubits," said Jeremy Béjanin, a PhD...
In a paper in Scientific Reports, a research team at Worcester Polytechnic Institute describes a novel light-activated phenomenon that could become the basis for applications as diverse as microscopic robotic grippers and more efficient solar cells.
A research team at Worcester Polytechnic Institute (WPI) has developed a revolutionary, light-activated semiconductor nanocomposite material that can be used...
14.10.2016 | Event News
14.10.2016 | Event News
12.10.2016 | Event News
28.10.2016 | Power and Electrical Engineering
28.10.2016 | Life Sciences
28.10.2016 | Life Sciences