Author(s): Anita Chandran
When you snap a selfie or film a video for social media, where does that information go? Find out how magnetic ‘storms’ could help us achieve better, faster data storage.
Every time you snap a photograph for Instagram or save your favourite video game, the information that you have generated has to be stored somewhere. With a population of eight billion people, all of whom are increasingly reliant on digital technologies, the amount of data we produce is growing! But where and how does this data get stored?
The data we produce is stored on desktop computers, laptops, and our smart phones, as well as on devices such as solid-state disk drives (SDDs), hard-disk drives (HDDs), or flash memory. These devices can be expensive, use energy, and take up space. “Hold on a minute,” you may say, “data can also be stored in the cloud, and that doesn’t require any space!” Although cloud-based storage doesn’t take up any room in your house, cloud storage devices are still based on physical computer servers, albeit ones that are distributed in a network of locations around the world.
The server rooms at European XFEL; home to the facility’s scientific data
© Jan Hosan/European XFEL
What does it mean to store data and how does this work?
All data in your computer is stored as a number, and all information can be converted into a numerical form. Take, for example, the alphabet. If you assign a number to every letter in the alphabet, and also assign numbers to spaces and punctuation, then you can easily write text with numbers. A similar process can be applied to colours in a photograph. More complicated pieces of information, like high-resolution videos, are data-rich and take up more storage space.
Binary numbers are used to encode information. This is because binary numbers are formed purely of 1s and 0s, which can represent the states ‘on’ (1, or ‘true’) and ‘off’ (0, or ‘false’) in an electrical circuit. On/off systems are simple and easy to set up. Although binary numbers are formed purely of 1s and 0s, they can be used to represent any numerical value. Computer scientists call pieces of information written in binary format ‘bits’. Combinations of bits give rise to packets of data, with the most common type of packet consisting of eight bits. This is known as a ‘byte’.
Once information has been transformed into bits and bytes, it is saved to a data-storage device. By using only 1s and 0s, you can tell a machine that something is on/true (1) or off/false (0). The storage device physically changes in some way to record the information as a series of true and false values.
Storage solutions such as HDDs or floppy disks use magnetic materials to store data, and have done since the 1980s. Magnetic materials can attract and repel one another through magnetic fields, patterns that describe the directions of the magnetic push and pull in a magnet. By using other magnets or electricity, the pattern of a magnetic field can be changed in certain materials to reflect a pattern of 0s and 1s, and this gives rise to data storage. Limitations arise from how quickly you can change the pattern (tell the material binary numbers, that is, ‘write’ the data) and how quickly you can determine what those changes are (‘read’ the data).
The magnetic field around a simple bar magnet: the arrows indicate the direction of the magnetic pull coming from the magnet
Image: P. Sumanth Naik/Wikimedia, CC BY-SA 3.0
Newer data-storage materials, such as those in your phones, laptops, and USB drives, use flash storage that is based on electrical charges instead of magnetic field patterns.
As we come to rely more on data, we need data storage solutions that are:
- Compact – the physical space needed to store data, particularly in server rooms, can be very large!
- Fast to save – we need to be able to save and handle large volumes of data as quickly as possible, to save everyone time.
- Environmentally friendly – data storage should be as energy efficient as possible and sustainable to manufacture.
Faster data storage by using tiny magnetic storms
Scientists around the world are looking for new methods of storing data that are faster and more energy efficient. To do this, they’re returning to magnetic materials and investigating an exciting type of magnetic structure known as a ‘skyrmion’.
So, what is a skyrmion? First conceived by British physicist Tony Skyrme in the 1960s, skyrmions are tiny magnetic storms that exist in the structures of magnets on atomic scales. You can think of them as resembling a very small spiral in the magnetic field. They can exist on their own, or in regular patterns known as lattices. These complicated miniature structures are extremely stable and require little energy to create or erase. This makes them an attractive candidate for smaller, more energy-efficient storage materials.
Although they don’t know how yet, scientists are convinced that they will one day be able to save information to media by using skyrmions and be able to read it back. Some studies suggest that creating and erasing skyrmions as a method of data storage could be almost 10 000 times more energy efficient than current devices.[1] Under the right conditions, scientists can use short bursts of light from a laser to create skyrmions in magnetic materials. But although these skyrmions can be generated, controlling and understanding their behaviour, and discovering how they can be adapted for data storage, is no easy task.
A short burst of laser light transforms a simple magnetic field (left) into a skyrmion swirl (right).
Image: B. Pfau, Max Born Institute
How can an X-ray free electron laser (XFEL) help us understand skyrmions?
An X-ray free electron laser (XFEL) can generate short bursts of X-ray radiation. These bursts of X-ray radiation are just a few tens of femtoseconds long. A femtosecond is one quadrillionth of a second long, or 1×10−15 seconds long (see the Timescale Infosheet in the supporting material). To put this in context, one femtosecond is to ten seconds, what ten seconds are to the lifetime of the universe (13.6 billion years). By using these extremely short bursts of radiation, scientists can observe the behaviour of skyrmions.
An experiment to investigate this phenomenon is being undertaken at the European XFEL, one of the world’s most powerful X-ray lasers, in Hamburg, Germany.
Scientists can use the European XFEL’s powerful X-ray laser beam, along withstate-of-the-art diagnostic techniques, to understand the behaviour of skyrmions. At European XFEL’s Spectroscopy and Coherent Scattering (SCS) instrument, scientists use an infrared laser beam to generate a skyrmion in a thin film of magnetic material, while simultaneously monitoring the process by using the X-ray beam. This allows them to monitor the formation of a skyrmion in a controlled manner.
By using the ultra-sensitive detectors and powerful X-ray beam at the European XFEL, researchers have been able to make new discoveries about the nature of skyrmions, showing that they can be created very quickly (in less than 300 ps) and in large quantities.[2, 3] This is vital for their use in reliable data storage.
European XFEL’s Spectroscopy and Coherent Scattering (SCS) instrument, where scientists are generating and measuring skyrmions
Image: European XFEL / Jan Hosan
This characterization pushes forward our basic understanding of magnetic phenomena, such as skyrmions. In other words, it tells us about fundamental physics, or the underlying nature of things. Developing our understanding of fundamental physics then enables engineers and companies to drive innovation, and improve technology for all of us. Though skyrmions may still have some way to go, these exciting magnetic whirlpools may yet revolutionise data storage!
