It’s a hot summer day. You desperately want something cold to drink, but unfortunately, your bottle of root beer has been sitting in a hot car all day. You put it into a bucket full of ice to cool it down. But it’s taking forever! How, you wonder, could you speed the process up? The same question is important for understanding how electronic devices work, and how we can make them work better by controlling the temperature of the electrons that power them. Read on to find out what a bottle of root beer in a cooler full of ice and a nanowire in a vat of liquid helium have in common!
Scientists are working to develop electronic devices that store and process information by manipulating a property of electrons called spin—a research area aptly known as spintronics. The semiconductors we are developing will not only be faster and cheaper than those used in conventional devices, but will also have more functionality.
Semiconductors are materials with properties intermediate between metals and non-conducting insulators, defined by the amount of energy needed to make an electron conductive in the material. The non-conducting electrons occupy a continuum of energy states, but two of these states (the “heavy hole” and “light hole”) are nearly identical in energy. The heavy hole is easy to observe and study, but the light hole eludes most observers.
Inside solids, the properties of photons can be altered in ways that create a kind of "artificial gravity" that affects light. Researchers at the University of Pittsburgh tracked photons with a streak camera and found that whey they enter a solid-state structure, they act just like a ball being thrown in the air: they slow down as they move up, come to a momentary stop, and fall back the other way. Studying this "slow reflection" will allow us to manipulate light's behavior, including its speed and direction, with potential applications in telecommunications and quantum computing technologies.
Neutron radiation detection is an important issue for the space program, satellite communications, and national defense. But since neutrons have no electric charge, they can pass through many kinds of solid objects without stopping. This makes it difficult to build devices to detect them, so we need special materials that can absorb neutrons and leave a measurable signature when they do. Researchers at the University of Nebraska-Lincoln are studying the effects of solar neutron radiation on two types of materials on the International Space Station (ISS), using detectors made of very stable compounds that contain boron-10 and lithium-6.
To increase our use of solar energy, we need to create more efficient, stable, and cost-effective solar cells. What if we could use an inkjet printer to fabricate them? A new type of solar cell uses a class of materials called perovskites, which have a special crystal structure that interacts with light in a way that produces an electric voltage. We've developed a method to produce perovskite thin films using an inket printer, which in the future could pave the way to manufacture solar cells that are surprisingly simple and cheap.
Think of the hard disk in your computer. Information is stored there in the form of magnetic "bits." But do you know how small a magnet can be? Some molecules make magnetic magic, and these special molecules may give rise to the ultrafast, high precision, low power devices of the future.
Carbon-based nanostructures are among the most intensely studied systems in nanotechnology. Potential practical applications span the fields of medicine, consumer electronics, and hydrogen storage, and they could even be used to develop a space elevator. A research team at the University of Northern Iowa is probing the properties of multilayered carbon nanostructures known as "carbon onions."
Scientists and engineers are making smaller and smaller structures designed to control the quantum states of electrons in a material. By controlling quantum mechanics, we can create new materials that do not exist in nature, develop more efficient solar cells and faster computer chips, and even discover exotic new states of matter.