  We present a multifunctional and multistate permanent memory device based on
lateral electric field control of a strained surface. Sub-coercive electrical
writing of a remnant strain of a PZT substrate imprints stable and rewritable
resistance changes on a CoFe overlayer. A proof-of-principle device, with the
simplest resistance strain gage design, is shown as a memory cell exhibiting
17-memory states of high reproducibility and reliability for nonvolatile
operations. Magnetoresistance of the film also depends on the cell state, and
indicates a rewritable change of magnetic properties persisting in the remnant
strain of the substrate. This makes it possible to combine strain, magnetic and
resistive functionalities in a single memory element, and suggests that
sub-coercive stress studies are of interest for straintronics applications.
