Exchange-driven Magnetic Excitation and Integrated Magnetoelectronics

Theory and recent experiments concerning exchange-driven magnetic excitation (EDME) are reviewed. This phenomenon employs the exchange field produced by a narrowly distributed spin-polarized electron current to excite Larmor precession in a magnetic film or particle. Predicted threshold currents for such excitation of both two-dimensional spin-waves and of monodomain reversal are now experimentally supported at both helium and ambient temperatures. The present status of this field suggests a high potential for applications of EDME to the write operation of magnetic recording and, when combined with tunneling magnetoresistance, to a memory latch using sub-200 nm lithography. This potential is buoyed by very recent experiments at Cornell University implying the theoretical availability of almost hundred-fold advantage in excitation efficiency favoring exchange fields over Maxwell fields.