All in a spin over magnet manipulation breakthrough

Current technologies for writing, storing, and reading information are either charge-based or spin-based. Semiconductor flash or random access memories detect electronic charge states to determine whether a data bit is a 1 or a 0. However, weak perturbations – such as impurities, temperature change or radiation – can lead to charge redistribution and data loss. Spin based devices, meanwhile, use electron spins to generate magnetism and the position of the north and south pole of the magnet can be used to store data. Applications ranging from magnetic stripe cards to hard disks use a spin based approach and are more robust against perturbations. However, to reverse the north and south poles of the magnet, the magnetic bit has to be coupled to an electromagnet or to another permanent magnet. Looking to address this, the researchers took a permanent GaMnAs magnet and applied an electric current inside it, creating an internal magnetic cloud which could manipulate the surrounding magnet. By demonstrating the poles can be flipped by an electric signal, the researchers believe a new generation of memories could be enabled, combining the merits of charge and spin based devices. "Ten years ago, we predicted and discovered how electric currents can generate pure spin currents through the intrinsic structure of materials," said Professor Jairo Sinova from JGU's Institute of Physics. "Now we have shown how this effect can be reversed to manipulate magnets by the current induced polarisation."