Magnetization chirality due to asymmetrical structure in Ni-Fe annular dots for high-density memory cells

Abstract

Ni–Fe asymmetric ring dots with partially planed outer sides were investigated as candidates for high-density magnetic memory cells. The magnetic states, which were measured with magnetic force microscopy, show that in-plane magnetic fields can control the chirality, either clockwise or counterclockwise, of vortical magnetizations of the Ni–Fe asymmetric ring dots. This control facilitates applying ring dots to the magnetic random access memories.

Shape and strain-induced magnetization reorientation and magnetic anisotropy in thin film Ti/CoCrPt/Ti lines and rings

“…[3][4][5][6] More recently, magnetic films patterned into stripes have been proposed for data storage 7 and logic applications, 8 and films with perpendicular anisotropy may be advantageous in these applications due to a lower critical current for current-induced domain-wall motion. [9][10][11][12][13][14][15] Thinfilm magnetic rings are also of considerable interest in nonvolatile multibit memory, biosensors, and logic devices based on giant magnetoresistence, [16][17][18][19] although rings with perpendicular anisotropy have not been explored.…”

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

“…6. Of course, when the exchange bias field is zero, the magnetic configuration is vortical and the direction of the vortical magnetization changes between clockwise and counterclockwise depending on the direction of saturation [10,11]. The computation shows that there is a required strength for the exchange bias field in order to pin the direction of vortical magnetization.…”

“…1 and demonstrated that the magnetization direction is controlled by in-plane unidirectional fields [10,11]. The above asymmetric ring layers can be used as free layers in the SV or MTJ ring memory cells.…”

Controlling the properties of vortex domain walls via magnetic seeding fields

“…[4][5][6][7] The ability to switch or set the sense of rotation and the polarity, i.e., the magnetization orientation of the vortex core, is a field of intense research. Recent publications demonstrate the possibility to change the sense of rotation in asymmetric single nanorings [8][9][10] and nanodisks 11 by applying external fields. The polarity can be manipulated via high-frequency electrical currents 12,13 or modulated magnetic fields.…”