Highly strain-sensitive magnetostrictive tunnel magnetoresistance junctions

Tunnel Magnetoresistance Sensors with Magnetostrictive Electrodes: Strain Sensors

“…Following our recent study [3] of magnetostrictive TMR sensors with the configuration in Figure 1d, we extend the work here with a numerical modeling, based on a modified SW model of resistance versus field ($R\left(H\right)$) loops as TMR sensors are exposed to different stress or strain quantities. This leads to better understanding of the magnetization reversal of the sense layer and allows one to figure out the optimum bias field required for high strain sensitivity.…”

“…The inverse impact on the angle α by tensile and compressive stresses results in an increase and a decrease of the tunnel resistance, respectively. This extends the applications further to detection of both tensile and compressive uniaxial stresses by a single sensor [3]. Such configuration is achievable, for instance, by internal couplings or an external bias magnetic field.…”

“…They are essential for applications that demand high strain sensitivity in small strain scales including force sensors, pressure sensors, and microcantilever technology [1,2]. Profiting from high sensitivity [3], high band-width [4], and miniaturization possibilities, magnetostrictive magnetoresistance (MR) sensors are a promising alternative to piezoresistive and piezoelectric strain sensors. In particular, magnetostrictive TMR sensors with CoFeB/MgO/CoFeB structures [3,5,6] offer more scalability compared to magnetostrictive giant magnetoresistance sensors [7,8,9,10] and higher gauge factors compared to AlO x -based TMR sensors with amorphous CoFeB [11], crystalline Co 50 Fe 50 [12] and amorphous (Fe 90 Co 10 ) 78 Si 12 B 10 [13] electrodes.…”

“…Profiting from high sensitivity [3], high band-width [4], and miniaturization possibilities, magnetostrictive magnetoresistance (MR) sensors are a promising alternative to piezoresistive and piezoelectric strain sensors. In particular, magnetostrictive TMR sensors with CoFeB/MgO/CoFeB structures [3,5,6] offer more scalability compared to magnetostrictive giant magnetoresistance sensors [7,8,9,10] and higher gauge factors compared to AlO x -based TMR sensors with amorphous CoFeB [11], crystalline Co 50 Fe 50 [12] and amorphous (Fe 90 Co 10 ) 78 Si 12 B 10 [13] electrodes. The CoFeB/MgO/CoFeB TMR sensors have been successfully incorporated into membranes for pressure sensing [5,14] and microcantilevers for atomic force microscopy (AFM) [6,15].…”

“…Up to now, MR-based strain sensors have been investigated in four different configurations [3,13,20] depicted in Figure 1. While the induced magnetic anisotropies or easy axes of the sense and reference layers are parallel (Figure 1a) or perpendicular (Figure 1b) to the stress axis, MR sensors only respond to compressive or tensile stress [13].…”