Magnetism: Materials and Processes for Tomorrow's Information Technology
Magnetic materials are at the basis of the high density storage devices embedded in everything from laptops to iPods. Increasing the storage capacity of these devices will require new ways to control the magnetism on an ever smaller scale. The ability of SwissFEL to produce beams of polarized X-rays sets the stage for potentially enlightening experiments on this field.
Tiny magnets keep the record.Ever wondered what keeps the pictures, songs and videos you have stored on your computer hard disk in place, after you switch the power off? The answer might astound you, it is magnetic data storage, the same technology that made now old-fashioned devices like recording tapes and floppy disks possible. Indeed, the hard disk drives (HDD) in your PC rely on similar technologies as those of the long forgotten cassettes that people once used to listen to music.
Pushing the boundariesIn the course of a few decades, the storage capacity of HDD has seen an astounding growth, but it will take new technologies to push the boundaries further in the future. Research with SwissFEL will make a contribution to faster and higher density magnetic storage devices. Nowadays, these devices hold their information on magnetized grains some tens of nanometers wide. Each of these grains represents one bit of information, and eight such Bits make one Byte. So if you for instance want to save a 1 Megabyte file on your hard disk, this file will occupy 8 Million magnetic grains (each representing one Bit). If you now want to change something in your file, this change might involve some hundreds or thousands of bits. This means that for the file to be changed, the state of hundreds or thousands of magnetic islands must be physically changed. This is where fast switching comes in. The faster you can switch the state (the magnetization) of an island, the faster your file will be changed. The gain in time may be insignificant if you are manipulating small files, but it will save you precious minutes when dealing with larger amounts of information.
Researchers have some ideas on how to achieve this faster switching with even smaller magnetic islands than the tiniest ones presently feasible. These smaller bits would mean that more information can be saved on the same physical area of a device. Thus, not only faster but also higher density magnetic storage devices could be made. At least, that's what computer simulations suggest. But to date no experiment has been done to verify these ideas