Ever since computers have been small enough to be fixtures on desks and laps, their central processing has functioned something like an atomic Etch A Sketch, with electromagnetic fields pushing data bits into place to encode data. Unfortunately, the same drawbacks and perils of the mechanical sketch board have been just as pervasive in computing: making a change often requires starting from the beginning, and dropping the device could wipe out the memory altogether.
As computers continue to shrink—moving from desks and laps to hands and wrists—memory has to become smaller, stable and more energy conscious. A group of researchers from Drexel University’s College of Engineering is trying to do just that with help from a new class of materials, whose magnetism can essentially be controlled by the flick of a switch.
The team is searching for a deeper understanding of materials that are used in spintronic data storage. Spintronics, short for “spin transport electronics,” is a field that seeks to harness the natural spin of electrons to control a material’s magnetic properties. For an application like computing memory, in which magnetism is a key element, understanding and manipulating the power of spintronics could unlock many new possibilities.
Current computer data storage takes one of two main forms: hard drives or random access memories (RAM). You can think of a hard drive kind of like a record or CD player, where data is stored on one piece of material—a hard disk—and accessed by a magnetic read head, which is the computer’s equivalent of the record player’s needle or the CD player’s laser. RAM stores data by encoding it in binary patterns of electrical charges called bits. An external electric field nudges electrons into or out of capacitors to create the charge pattern and encode the data.
To store data in either type of memory device we must apply an external magnetic or electric field—either to read or write the data bits. And generating these fields draws quite a bit of energy. In a desktop computer that might go unnoticed, but in a handheld device or a laptop, quality is based, in large part, on how long the battery lasts.
Spintronic memory is an attractive alternative to hard drives and RAM because the material could essentially rewrite itself to store data. Eliminating the need for a large external magnetic field or a read head would make the device less power-intensive and more rugged because it has fewer moving parts.
While spintronic materials have been used in sensors and as part of hard drive read heads since the early 2000s, they have only recently been explored for direct use in memories. Taheri’s group is closely examining the physical principles behind spintronics at the atomic scale to look for materials that could be used in memory devices.
Theoretically, spintronic storage could encode data by tuning electron spins with help from a special, polarized electrical current running through the material. The binary pattern is then created by the “up” or “down” spin of the electrons, rather than their presence “in” or “out” of a capacitor.
To better understand how this phenomenon occurs, the team took a closer look at structure, chemistry and magnetism in a layered thin film oxide material that has shown promise for use in spintronic data storage, synthesized by researchers at the University of Illinois—Urbana Champaign.
The researchers used advanced scanning transmission electron microscopy, electron energy loss spectroscopy and other high-resolution techniques to observe the material’s behavior at the intersections of the layers, finding that parts of it are unevenly electrically polarized—or ferroelectric.
They also used quantum mechanical calculations to model and simulate different charge states in order to explain the behavior of the structures that they observed using microscopy. These models helped the team uncover the key links between the structure and chemistry of the material and its magnetic properties.
This story is reprinted from material from Drexel University, with editorial changes made by Materials Today. The views expressed in this article do not necessarily represent those of Elsevier. Link to original source.