Posts showcasing the wonder, beauty, and potential of cutting-edge materials research—freely contributed by physicists from across the country. (Funsize Physics is not responsible for any minds that are blown.)
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!
Diodes, also known as rectifiers, are a basic component of modern electronics. As we work to create smaller, more powerful and more energy-efficient electronic devices, reducing the size of diodes is a major objective. Recently, a research team from the University of Georgia developed the world's smallest diode using a single DNA molecule. This diode is so small that it cannot be seen by conventional microscopes.
Biophysics is a field that applies knowledge of physics to understand and explain biological phenomena. Biophysicists study life at different levels, from atoms and molecules to cells, organisms, and their environments. They focus on questions such as how proteins function, how nerve cells communicate, how viruses invade human cells, how plants absorb sunlight and convert it into food, and so on. Biophysics has contributed significantly to improving human health in multiple ways, and the study of protein-protein interactions is an especially important biophysical topic. By exploring the molecular basis of complicated biomedical diseases, biophysicists help to develop methods to treat these diseases.
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.
You may know helium as the gas that can make balloons and blimps float. At the University of Maryland, scientists are using this element to study the exotic physics of quantum vortices: the tornadoes or bathtub-drain whirls of the quantum world. Knowing how quantum vortices work could help us better understand other turbulent events (like wind and ocean currents), as well as the complex physical behavior of superconductors and neutron stars.
How can you fabricate a huge number of nanostructures in a split second? Self-assembly is a fast technique for the mass production of materials and complex structures. But before self-assembly is ready for prime time, scientists need to establish ways to control this process, so that desired nanostructures emerge from the unstructured soup of basic building blocks that are fast-moving atoms and molecules.
We tend to think of materials as either electrical conductors or insulators: some materials, like metals, have low electrical resistance and conduct electricity easily, while others, like wood or plastic, have high electrical resistance and do not readily conduct electricity. Strange experimental results, however, reveal large fluctuations in the electrical resistance of thin metallic nanowires when a magnetic field or charge difference is applied to them. Click to learn how a more nuanced understanding of electron behavior helps to explain these variations in electrical resistance that may revolutionize the tech industry!
Instead of pencil, paper, and eraser, we can use combinations of lasers and magnetic materials to write, read, and and erase information by varying the temperature and magnetic field. Here we apply our laser "pencil" to magnetic "paper" to write the letter “N” (Go Cornhuskers!!). This technique allows us write, erase, and rewrite tiny magnetic memories like those found in your computer hard drive and other devices, using a precise, non-contact tool. Click to learn more about how it works!
Recent progress in materials science has led to the creation of new magnetic materials in which the magnetism follows complex patterns. The formation of these patterns depends on a phenomenon called spin-orbital coupling. Because they can be manipulated by electric currents and temperature changes, materials exhibiting these interesting magnetic patterns may have applications in magnetic memories and logic devices. Click to learn how!
Solids are generally divided into metals, which conduct electricity, and insulators, which do not. Some oxides straddle this boundary, however: a material's structure and properties suggest it should be a metal, but it sometimes behaves as an insulator. Researchers at the University of California, Santa Barbara are digging into the mechanisms of this transformation and are aiming to harness it for use in novel electronic devices.
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.
Most electronics are made out of rigid materials like silicon, but it is possible to make wires and other electronics using entirely soft and squishy materials. By utilizing liquid metal nanoparticles, we can even draw wires by hand using light pressure from a magic marker to squish the particles together.
At low temperatures, helium—the same substance that makes balloons float—becomes a special type of liquid known as a superfluid, which has zero viscosity. It's like the anti-molasses! The properties of superfluids are governed by the laws of quantum mechanics. More specifically, the atoms in superfluid helium are “entangled” with each other, allowing them to share information and influence each other’s behavior in ways that are totally foreign to our everyday experience, and which Einstein famously described as "spooky action at a distance." Better still, scientists have recently discovered that the law controlling entanglement between different parts of a helium superfluid is the same as that governing the exotic behavior of black holes in outer space.
Very small structures, much smaller than the human eye can see, often fall in the size range of nanometers. By understanding how the molecules that make up these structures interact, we can engineer them to do many special things that cannot be done at a larger scale. One exciting structure is a polymer brush, in which long, chain-like molecules called polymers are tethered at one end to a surface and stick up from the surface like bristles on a hairbrush. Polymer brushes can be used to keep bacteria away, provide an exceptionally smooth surface for items to slide across, or trap other molecules in solution like a hairbrush traps loose hair. In order to engineer polymer brushes that will perform as desired for a given application, we must understand the physics of how the molecular bristles move, and the chemistry of how they interact with their environment.
The electric eel's ability to generate incredibly large amounts of electric power from within its body has fascinated scientists for centuries. In fact, some of the world’s first batteries were inspired by studies of this amazing animal. Now, scientists have developed a new eel-inspired energy source that may one day be used to power electronics implanted within the human body.
Many solid materials have a crystal structure, with atoms that exist in a particular, organized arrangement. The degree of organization can vary among crystals, however. High-quality crystalline materials are the foundation of many familiar devices, such as integrated circuits and solar cells. A better understanding of these materials and how to produce them is important for developing new technologies.
In phase-change memory (PCM), nanoscale volumes of a special kind of glass compound are heated by very short electrical pulses, causing the atomic structure of the material to switch between an ordered phase and a disordered phase. These phase-change materials have been used for years to store data on rewritable CDs and DVDs, but until recently, the large energy required to change the state of the material has made it impractical for electronic memory. If this challenge can be overcome, phase-change memory can be integrated with conventional silicon electronics for high-capacity data storage and more efficient computation. Click to read more about how we are working to make this new technology a reality!
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."
You may know that the media used in magnetic recording technologies, such as computer hard drives, are made of millions of tiny nanomagnets. Each nanomagnet can be switched up or down to record bits of information as ones and zeros. These media are constantly subjected to magnetic fields in order to write, read, and erase information. If you have ever placed a magnet too close to your laptop or cell phone, you know that exposure to an external magnetic field can disrupt information stored this way. Did you know that it is possible for the nanomagnets to "remember" their previous state, if carefully manipulated under specific magnetic field and temperature conditions? Using a kind of memory called topological magnetic memory, scientists have found out how to imprint memory into magnetic thin films by cooling the material under the right conditions.
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.
In a unique state of matter called a superfluid, tiny "tornadoes" form that may play an important role in nanotechnology, superconductivity, and other applications. Just as tornadoes are invisible air currents that become visible when they suck debris into their cores, the quantum vortices in superfluids attract atoms that make the vortices visible. Quantum vortices are so small they can only be imaged using very short-wavelength x-rays, however.