Operational Amplifier Circuits for Magnetic Sensing Using Perpendicular Low-Coercivity Nanoscale Spin Transfer Torque Magnetic Tunnel Junctions

Authors:
Publisher website
Google Scholar
Abstract
This paper presents the use of nanoscale perpendicular spin transfer torque magnetic tunnel junctions as magnetic sensing units in which the conditioning electronics consists of simple circuits based on operational amplifiers. This approach allows low power (μW), nanoscale (50 to 100 nm) and high-frequency (100 kHz to 1000 kHz) magnetic measurements, with, in addition, presenting CMOS compatibility for future mass production. Noises levels as low as 2 μT/√Hz are achieved over a dynamic range of up to tens of mT. The different circuits are demonstrated through theoretical modelling and confirmed with experimental measurements on fabricated devices, validating the working principle with sensing elements among the smallest ever reported to our knowledge. Further improvements are however required, in both the proposed electronics and stacks of the junctions, to lower the noise and reach the sub-μT noise level. Hence, this technology could open the way to new metrological possibilities, unaddressed with existing technologies, including photolithographic mask alignment or high-frequency current measurements, in the case of industrial applications, as well as measurements of magnetic beads and ferromagnetic particles detection in life sciences.
Funding Information
  • Swiss Nanoscience Institute (A18.6)
  • European Research Council (ERC-2022-PoC2)
  • National Research Agency in the Frame of France 2030 (ANR-22-EXSP-0006 ADAGE)

This publication has 18 references indexed in Scilit: