Tunnel Magnetoresistance Sensors with Magnetostrictive Electrodes: Strain Sensors

Abstract

Magnetostrictive tunnel magnetoresistance (TMR) sensors pose a bright perspective in micro- and nano-scale strain sensing technology. The behavior of TMR sensors under mechanical stress as well as their sensitivity to the applied stress depends on the magnetization configuration of magnetic tunnel junctions (MTJ)s with respect to the stress axis. Here, we propose a configuration resulting in an inverse effect on the tunnel resistance by tensile and compressive stresses. Numerical simulations, based on a modified Stoner–Wohlfarth (SW) model, are performed in order to understand the magnetization reversal of the sense layer and to find out the optimum bias magnetic field required for high strain sensitivity. At a bias field of −3.2 kA/m under a 0.2×10-3 strain, gauge factors of 2294 and −311 are calculated under tensile and compressive stresses, respectively. Modeling results are investigated experimentally on a round junction with a diameter of 30±0.2sans-serifμm using a four-point bending apparatus. The measured field and strain loops exhibit nearly the same trends as the calculated ones. Also, the gauge factors are in the same range. The junction exhibits gauge factors of 2150±30 and −260 for tensile and compressive stresses, respectively, under a −3.2 kA/m bias magnetic field. The agreement of the experimental and modeling results approves the proposed configuration for high sensitivity and ability to detect both tensile and compressive stresses by a single TMR sensor.

Temperature dependence of transport mechanisms in organic multiferroic tunnel junctions

“…The TER is much enhanced and reaches about 200% at RT with the second polarization method. This study gives 27 a strong argument that the decreasing of TER for the temperature range higher than 120K is mainly due to the thermal fluctuation on the ferroelectric domains.…”

Comprehensive Analysis of the Energy Harvesting Performance of a Fe-Ga Based Cantilever Harvester in Free Excitation and Base Excitation Mode

“…Some studies [53,54,55] have shown that pre-magnetized magnetic fields have an effect on the Villari effect of magnetostrictive materials, so we speculated that it also has an effect on the performance of Fe-Ga harvester. We adopt a permanent magnet to provide a pre-magnetized field to the Fe-Ga layer and select three different pre-magnetized positions and layouts to carry out this experiment.…”

Magnetic Micro Sensors with Two Magnetic Field Effect Transistors Fabricated Using the Commercial Complementary Metal Oxide Semiconductor Process

“…The system includes an MMS, an inertial sensor, a global positioning system receiver, a vision component, and a navigation algorithm to stabilize and control the flight of an unmanned aerial vehicle. A tunnel magnetoresistance MMS, designed by Tavassolizadeh [6], has been applied in sensing micro-and nano-scale strain. The experiments showed that the tunnel magnetoresistance MMS has an ability to measure both compressive and tensile stresses.…”