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

Abstract

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 4–5Ω/□. 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 2.7×106 A/cm2. 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 Ω) 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.

Giant Magnetoresistance Based Biosensors for Cancer Screening and Detection

“…Conversely, when the magnetizations are antiparallel, the scattering is strong, leading to high resistance. The GMR effect has had significant implications in various technological applications, particularly in the field of magnetoresistive random-access memory (MRAM), where it has enabled the development of high-density, nonvolatile memory devices with improved performance and efficiency. − …”

Magnetically pinned ring dots for spin valve or magnetic tunnel junction memory cells

“…Future magnetic memory cells for magnetic random access memories (MRAMs) [1][2][3][4] should have highly dense arrangements to store large amounts of information. However, a high-density arrangement enhances the effects of stray fields from adjacent memory cells on each memory cell, which decreases the uniformity of the switching fields of free layers [5] in spin valve (SV) or magnetic tunnel junction (MTJ) memory cells.…”

Synthesis and magnetotransport properties of nanometric spin valve arrays fabricated by electrodeposition

“…One of the spin-dependent devices, which utilizes the giant magnetoresistance (GMR) effect, is a spin valve sensor. Recently interest has increased dramatically in using a pseudo spin valve whose operation depends on the coercivity difference between two ferromagnetic layers, which are separated by a non-magnetic layer in MRAM devices [7][8][9][10]. The requirement for high-density magnetic memory has driven research to the nanoscale [11,12], and memory cells composed of spin valves have been considered for MRAM [13,14].…”