Magnetoelectronic characteristics of a GMR transpinnor and a magnetic random access memory using a closed-flux NiFe/Cu/CoFe/Cu/NiFe pseudo spin-valve

The magnetoelectronic device characteristics of a GMR "transpinnor," a new multifunctional solid-state device, and a magnetic random access memory (MRAM) have been investigated using the structure of closed-flux NiFe/Cu/CoFe/Cu/NiFe pseudo spin-valve (PSV) for a new current driver-one MRAM cell architecture on the same substrate. The electrical and magnetic device characteristics of a PSV-MRAM cell and single or dual-input "transpinnors" are a GMR ratio of 3%-6% and a sheet resistivity of 4-5Omega/square. The switching characteristics of PSV MRAM cells were measured using patterned Si/Si3N4/PSV with a NiFe(30 nm)/Cu(90 nm) word or input line. The writing field was set at +/-40 Oe and a 1-3 mV output signal was obtained when a 10.2 Oe sensing field was induced by a word line with a current density of 2.7x10(6) A/cm(2). The output characteristics of the GMR "transpinnor" were measured using a PSV fabricated on the same wafer with the MRAM cell. Similar to standard transistor characteristics, the transpinnor exhibits a very high output signal between 2 and 3 mA (output load R=1 Omega) at a low 8 Oe switching field, which should be potentially useful as a current driver for activating PVS-MRAM circuits and for realizing various new logic gates such as OR, NAND, and other multivalue logic states. (C) 2002 American Institute of Physics.