  Spintronics is a new paradigm for integrated digital electronics. Recently
established as a niche for nonvolatile magnetic random access memory (MRAM), it
offers new functionality while demonstrating low power and high speed
performance. However, to reach high density spintronic technology must make a
transition to the nanometer scale. Prototype devices are presently made using a
planar geometry and have an area determined by the lithographic feature size,
currently about 100 nm. Here we present a new nonplanar geometry in which one
lateral dimension is given by a film thickness, the order of 10 nm. With this
new approach, cell sizes can shrink by an order of magnitude. The geometry is
demonstrated with a nonlocal spin valve, where we study devices with an
injector/detector separation much less than the spin diffusion length.
