Magnetic tunneling junction with Fe/NiFeB free layer for magnetic logic circuits

Abstract

We have developed a shape varying magnetic tunneling junction (SVM) with a Fe/NiFeB free layer for use in magnetic logic circuits. Inserting the thin Fe film between an NiFeB free layer and MgO tunneling barrier improved the magnetoresistance (MR) ratio: it increased up to 130%, as the thickness of the Fe film increased. In addition, the switching current distribution of the SVM was reduced to 8%. By using NiFeB as a free layer, the roughness under the MgO was reduced and the crystallization of the MgO was enhanced. This led to both the high MR ratio and the low switching current distribution. Our developed Fe (0.4 nm)/NiFeB free layer satisfies the requirement of the MTJ's characteristics that the magnetic logic circuits operate with a high bit yield.

Plasma process induced physical damages on multilayered magnetic films for magnetic domain wall motion

“…1(b). [15][16][17] One of the challenges in fabricating the device structure is how to pattern two separate HLs just over the FL. Figure 2 shows the schematics of the fabrication flow of the HL pattern over the FL, and the evaluation of the DW motion using the sensor MTJ.…”

“…Details of this subsequent fabrication procedure were discussed elsewhere. 15,16) Several other physical analyses were carried out to clarify the etching end-points and the sample surface conditions. A vibrating sample magnetometer (VSM) was used to measure magnetization hysteresis loops.…”

“…Device applications of the DW motion have been investigated, such as race track memory for storage, 13) and logic/memory devices. [14][15][16][17] In each case, the magnetic nanowire is assigned as the FL in the devices, and it stores 0/1 information for different magnetization directions. To read such information, the magnetization direction at a certain position of the nanowire is detected by the MTJ.…”

“…To read such information, the magnetization direction at a certain position of the nanowire is detected by the MTJ. The important advantages of DW-motion devices are high-speed 15,16) operation performance by nature 18) as well as a high electrical endurance. 19) No need of high-current flow across a tunnel barrier oxide during information write is also another advantage of these devices over the usual MTJ for spintransfer switching.…”

“…Details of the DW-motion devices were given elsewhere. [15][16][17] A variety of plasma processes are used to fabricate these spintronics devices. Stacked magnetic thin films are usually deposited by physical vapor deposition (PVD) with magnetic field assistance for plasma generation.…”