We live today in a digital era, with very sophisticated electronic devices such as computers and mobile phones forming part of our daily life. These devices are simply amazing, and have changed the way humans work, make use of their free time and interact with each other. This radical transformation in our society has happened in just a few decades, which has been possible thanks to the great combined effort of scientists and engineers. However, as in any revolution in human history, an essential question that we should ask ourselves is: were we ready for this revolution, and are there negative consequences that we should identify and try to fix? This question will bring to your minds different ideas: There are security problems associated to how electronic data are handled, for instance the hacking scandal in the last US elections. Ethical and philosophical issues such as if an education dominated by technology is the best way to bring up our children. Or in general, if the great dependence that we have now on these devices makes us a better, stronger, more advanced society. There’s another very important drawback in this story, which is actually the one motivating my research. This is the very large amount of power consumed by computing devices worldwide. The evolution of computing devices has been possible due to the miniaturization of integrated circuits. Integrated circuits are the electronic circuits forming a computer. Integrated means that the electronic components such as transistors forming the circuit have been directly fabricated on the surface of a Silicon chip. Because of this, they can be made extremely small, with billions of them now fitting a very small area. This is why we have light and powerful computers today, with large memory and processing power. However, more processing power means more power consumption. Still, computers, laptops and mobile phones consume less energy than many appliances at home. However, the number of these devices worldwide is increasing rapidly: an average person may own now two, three, four, ten? devices, including personal computers, laptops, tablets and phones. There is now a growing concern about the total energy consumed by humans when using technology. Up to the point that it is starting to be a relevant factor for carbon emissions and it could become a long-term threat for the environment. In order to illustrate how important this problem is today, let’s take a look at the big data centres such as Google or Facebook. These deal with a huge amount of information, associated to the web and social media on a global scale. The thousands and thousands of computing units in the centre generate a huge amount of heat. This is why these centres are usually located in cold areas of the planet, and require a gigantic cooling infrastructure.
In fact, according to some sources, if we imagine all data centres forming a single country, this would be the 5th on the list of countries which consume more energy in the world. And this is expected to get even worse in the coming years, since we –humans- are using more technology every day. So in order to tackle this very serious threat, it is of vital importance to develop greener technologies, based on radically new, different mechanisms.
Many scientists and engineers worldwide are investigating different approaches. In my case, I use nanotechnology and magnetism. Nanotechnology is the area of technology dealing with systems at the nanoscale, which is normally defined to be between 1 and 100 nanometer (nm). In order to have an intuitive idea of what these dimensions really mean, let’s look at this ruler. Please focus your attention on the 1 mm scale. Imagine now that you divide this length by 1,000; that length is 1 micron (μm): this distance would be of the same scale as some cells and bacteria. Now divide that distance 1,000 times more: that very small length is 1 nm, which would correspond to about the size of 10 atoms.
Silicon transistors forming integrated circuits in electronic devices are already nanometric, where each bit of information is stored as an electrical charge on a given area of the memory. Normally, a continuous input of energy is needed for this bit to remain in memory and not get erased over time. Also, every time there is a computation, bits are transferred from the memory to the processing unit (CPU), travelling back to memory after the computation. This data transfer between memory and CPU also requires a significant amount of energy. As you can see, the current computing architecture could be more efficient. A great improvement would result if bits were stable in memory without needing a continuous supply of energy, and if memory and CPU were merged together. This means creating a new computing architecture, a new paradigm for computation. This is why my colleagues and I at the University of Cambridge, are investigating the possibility of creating new chips based on networks of magnetic nanowires. A magnetic nanowire is a wire with a diameter at the nanoscale, and a length of a few microns, and has outstanding properties for green computation: Due to its elongated shape, it can store many bits along its length, which can move as tiny confined packages when applying small pulses of current through it. Because it is made of magnetic materials, data is stored without needing a continuous supply of energy. And it is not only great for storage and transmission of data, but it can also perform computations: this is achieved simply by playing with the shape of the wire, and by connecting it to other wires, creating particular geometries.
Many scientists have been studying the properties of magnetic nanowires during the last decade, discovering fascinating new effects. The great challenge now in order to make this technology commercially feasible is to increase the storage capacity of integrated circuits based on them. And this requires an additional radical change, which is creating three-dimensional chips for the first time. Because all integrated circuits that exist and have ever been fabricated are two-dimensional; formed by a plane of transistors and interconnectors, data is confined just to the plane of the 2D chip. This is not casual, and is due to a fundamental manufacturing bottleneck: current nanofabrication methods are able to create complex functional 2D (but not 3D) nanostructures. In order to overcome this limitation, our group in Cambridge is investigating new 3D nanofabrication techniques based on the use of electron microscopes and gases. We’re doing this in close collaboration with other groups, including some in the US and here, in Zaragoza. Electron microscopes are one of the most versatile and powerful tools in nanotechnology. By employing electrons instead of conventional light, they are capable of imaging structures at the nanoscale in great detail. In our case, we don’t use these microscopes just for imaging, but also as 3D nano-printers. The images you see below have been created with this technique, and have features about 1,000 times smaller than what the best 3D printer on the market can do today .
This 1-step nanofabrication technique is conceptually much easier than conventional manufacturing methods used by the microelectronics industry, which require tens of steps. But it is not yet suitable for massive mass-production; this will be possible once we find ways to make the technique cheaper and faster. In my lab, we’re exploring if the 3D magnetic nanowires manufactured this way have the properties needed for computing applications. We still need to solve key challenges. For example, how to make the wires of better materials, since otherwise we cannot have smooth flow of bits through them. Also, most nanotechnology methods are designed to detect and image 2D objects. We are now creating new ways to resolve the magnetic properties at the nanoscale in 3D. I find very exciting that we’re now closer to create electronic circuits which will be greener and that will have novel functionalities. This will make computing devices more independent of energy sources, becoming much less of a concern for the global warming of the planet. In order to achieve this, I would like to plead for a society that is aware of the challenges of the future. A society that supports research to advance and overcome these challenges. And that makes a responsible use of technology, so that coming generations can continue enjoying our now, technological world.
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