Linearization strategies for high sensitivity magnetoresistive sensors

Abstract

Abstract. Ultrasensitive magnetic field sensors envisaged for applications on biomedical imaging require the detection of low-intensity and low-frequency signals. Therefore linear magnetic sensors with enhanced sensitivity low noise levels and improved field detection at low operating frequencies are necessary. Suitable devices can be designed using magnetoresistive sensors, with room temperature operation, adjustable detected field range, CMOS compatibility and cost-effective production. The advent of spintronics set the path to the technological revolution boosted by the storage industry, in particular by the development of read heads using magnetoresistive devices. New multilayered structures were engineered to yield devices with linear output. We present a detailed study of the key factors influencing MR sensor performance (materials, geometries and layout strategies) with focus on different linearization strategies available. Furthermore strategies to improve sensor detection levels are also addressed with best reported values of ∼40 pT/ √ Hz at 30 Hz, representing a step forward the low field detection at room temperature.

Remote microwave monitoring of magnetization switching in CoFeB/Ta/CoFeB spin logic device

“…[6][7][8][9] Practical applications of the MI are monitoring of GMR sensor switching sensitive to proteins labeled by ferromagnetic nanoparticles (so called medical spintronics). 10,11 The method proposed in our article looks similar to MI measurements of the impedance in the magnetic field [6][7][8][9] except the high frequency ($10 GHz) microwave field in our work, instead of comparatively low frequencies in the MI experiments limited by the 10-100 MHz range. The advantage of the microwave monitoring proposed in our article is wireless detection of the stable states of the GMR devices and possibility to study anisotropy of their magnetoresistance.…”

Magnetoresistive Sensor Development Roadmap (Non-Recording Applications)

“…For TC 1.2, the saturation field 2μ0Hsat around 0.08 mT was demonstrated by combining the sensor with a Conetic MFC (gain: ~77 times) in 2011 [243]. In 2015, a factor of 400 times MFC was reported for an MTJ bridge [315]. In 2017, Valadeiro et al reported a high gain (~400 times) MFC with a double layer architecture [310].…”

Multiple Giant-Magnetoresistance Sensors Controlled by Additive Dipolar Coupling

“…A linear variation of the GMR resistance with the magnetic field with a low hysteresis is obtained when the easy magnetization axis of the free layer is set perpendicular to the pinned layer. This is achieved through the shape anisotropy 27 by patterning the yoke arm length perpendicular to the pinned layer magnetization as shown in Figure 2(a). The sensor magnetoresistance evolution with the number of GMR repetitions and constant width w= 4 µm is shown in Figures 2(b-c).…”