Graded Magnets Pave Way for More Efficient Memories
We have discovered that non-uniform, “graded” magnets could make digital memories more energy-efficient. Our research introduces a new approach to engineering “spin-orbit torque” memories, where an electric current generates a torque that switches the magnetic information in the device.
Traditionally, these devices use a thin magnetic film, coupled with another non-magnetic material to create the torque. But this poses a problem: while a thinner magnet enhances the torque, it increases magnetic damping, which (like friction) hampers efficient switching.
We present a breakthrough with a single-layer film, which is entirely magnetic and nearly ten times thicker than its predecessors. The key lies in the magnet’s atomic composition or structure, which gradually changes across its thickness. A sizable torque arises within this graded magnetic layer, while the damping remains roughly ten times lower than previous devices.
Interestingly, our work shows hat a significant structural gradient can form naturally during the magnetic film’s synthesis, as atoms are stretched or compressed differently at the top and bottom. These findings highlight how both deliberate and natural gradients in magnetic films could drive the next generation of greener information technologies.