GMR effect in nonhomogeneous magnetic field

Abstract

Magnetic field sensors, based on giant magnetoresistance (GMR) effect, have a wide range of practical implementations. One of them is the use as a positioning device in different kind of actuators. Here we report on modelling of magnetoresistivity response of spin-valve (SV) based GMR structure in a various geometry of SV positioning with respect to a magnetic reference label. The model includes the magnetic label of a certain shape producing a nonhomogeneous magnetic field in 3D space and moving along a straight line in front of SV device. Different mutual label-SV positioning is considered. The reaction of micromagnetic configuration in the ferromagnetic layers and corresponding magnetoresistive effect of the SV is calculated and analyzed.

Clusters of Spin Valve Sensors in 3D Magnetic Field of a Label

“…The observed features can be interpreted based on consideration of the output signal of a single SV sensor in the field of a magnetic label reported previously. In particular, the case in Figure 4 a corresponds to case 2.1 in Babaitsev et al [ 33 ], when the magnetic moment of the R1 sensor has components M = {Ms, 0, 0} in the initial state. Non-monotony is due to two factors, besides the distance between the sensor and the label.…”

“…The method of calculating the 3D components of the magnetic field of the label, H(R) , was reported earlier [ 32 ]. A similar method was used in our previous papers [ 33 , 34 ] to calculate the fields of permanent magnets of several forms (parallelepiped, cylinder, etc.). We chose the Cartesian coordinate system connected with the label placed at the origin and with magnetic moment oriented along the z-axis.…”

“…We follow the variation of the sensor signal during the motion along the trajectory, i.e., we study the variation of the signal depending on the sensor location relative to the label and on the relative mutual orientation of the sensor and the magnetic label. The results for orientations of 6 single sensors were given in Babaitsev et al [ 33 , 34 ] are used here for clusters of SV sensors.…”

“…Further on, the model assumes that the rotation and equilibrium state of magnetization are achieved instantly. An in-depth consideration of signal features of a single SV sensor moving in a magnetic field of a label can be found in Babaitsev et al [ 33 , 34 ]. In this paper, we study the signal of a cluster of sensors instead of a single SV sensor.…”