I was always fascinated by the fact that information is stored in a “two letter” alphabet expressed by binary digits (in short: ‘bits’). Yes, only two digits, 0 and 1, store a hell of a lot of data in our computers around the globe. This fact sounded like magic to me when I first heard about it as a kid. But over the years I came to the realization that it isn’t magically possible, but magnetically possible instead. Yes, magnetism is the way used to store your information in the hard disk of your computer. Aha!

Let’s get to the basics, and once you roughly understand the principle, it starts to make a whole lot of sense. If you ever bother to open a hard disk, you have certainly seen a shiny circular plate. This plate is divided into billions of tiny magnetic areas that can be magnetized in two opposite directions, thus differentiating the integer “1” or “0”. Why, for heaven’s sake? Well, when the computer reads the data, the 1 and 0 must be detected somehow and the data must be kept stored even if the power of the computer is off. Overall, it is handy to use magnetism because once something is magnetized; it basically stays this way until you do the inverse process.

Now let’s think about capacity of storage. If you have only one of these shiny plates to store all your info, the number of tiny magnetic areas on the surface will limit its capacity. The puzzle-solving research starts at this point. We all live in an ever-increasing digitalized world that seeks larger and larger storage capacities. Here is where my PhD becomes of relevance. In order to increase the hard disk capacity keeping the same plate surface, we can ideally decrease these tiny areas to the size of a single atom and use what we call the spin of an electron, which is a kind of a tiny magnet hanging to the electron - to do the magnetizing trick. In fact, the spin can also store the information 0 and 1 because we can easily orientate it to different directions. But going to an atomic level isn’t as straightforward as you may imagine. Much research is still needed to improve our understanding, first on a physical level, in order to eventually one day bring this knowledge to the level of building a hard disk.

The final take-home message is: If you compare the size of one atom with the size of one actual tiny spot in your hard disk today, it’s as if you compare the size of a tennis ball with the Earth’s size! How much more storage would you get then? I am sure it sounds magical to you now, too!

I am Christopher Vautrin, a PhD student working at the Jean Lamour Institute at the University of Lorraine.

Text by Fernanda Haffner

Illustration by Luis Rubio

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