Researchers at the Max Planck Institute of Microstructure Physics have created a memory element with four states. The element consists of a sandwich of ferromagnetic and ferroelectric materials. Using a short electric pulse it is possible to change the electrical and magnetic properties of the element. The new technique allows placing information in four instead of just two states of a memory element, increasing storage density.
The multiferroic sandwich was created by steaming an extremely accurately structured ferromagnetic lanthan strontium manganate (LSMO) layer on a base. The thickness of this layer is just under 30 nm. On top of that, a layer of ferroelectric lead zirconate titanite (PZT) only three nanometres thick and with a very regular structure was deposited; a top layer of ferromagnetic cobalt finished the sandwich.