The aim of the project is to develop a novel characterization tool of the magnetic properties of the material surface at nano-scale by combining very sensitive magnetoresistive (MR) sensors and atomic force microscopy. This tool will have three main innovative applications: magnetic nanometrology, magnetic susceptibility imaging and micro imaging of Nuclear Magnetic Resonance (NMR) spectroscopy
The AFM allows a control of the tip height and its displacement while the magnetic sensor integrated in the AFM tip measures the magnetic field at each position. This combination is the original part of this project which will lead to a new tool opening new perspectives for material characterization and analysis, regarding especially in situ following, non destructive testing and nanometrology. <br /> <br />The first objective of the project is to develop MR sensor integrated in AFM cantilever. To achieve this objective, three processes will be developped: nano-GMRs, nano-TMRs and MR sensor integrated inside flexible cantilever. The characterization of the sensors produced will be then performed. <br /> <br />The second objective is to develop a versatile MR microscope able to measure topology, DC and AC fields, with hundreds of nm resolution and a detectivity of between the nT and the pT/vHz. The task will consist in building this microscope, integrating the modified cantilever with optimized MR sensors fabricated during the task 1 and to performed tests on calibrated samples. Then, the addition of modules to the microscope will be done to create new and original functionalities towards multifunctional local probe microscopy: magnetic susceptibility microscopy and local NMR mapping. Ultimate goal will be to validate the two functionalities, susceptibility and NMR on model systems, which will also demonstrate the capabilities of the technique.
The manufacturing process of nanoGMRs and cantilever with integrated GMR sensor have been developed
During this first part of the ANR, several GMR sensor optimization studies were carried out (Julien APL 2019 and Torrejon PRA 2020). The manufacturing process of nanoGMRs and cantilever with integrated GMR sensor have been developed and allowed the characterization of their performance. These tips were then integrated into the microscope and the electronics developed enabled the acquisition of topographic and magnetic images of the stray field emitted by a calibration sample (current loop). Simulations were also carried out and are in very good agreement with the measurements.
Concerning the task of using MRs sensors to perform NMR on a local scale. The setup has been developed and GMRs micron sensors manufactured. The static field required for NMR pulls the magnetic layers of the GMR out of the plane which induces a decrease in sensitivity and field inhomogeneity that makes local NMR measurement very difficult. This leakage field has been characterized by MFM and VSM. Different techniques for reducing this stray field were studied.
The development of the setup to allow the measurement of the magnetic susceptibility is in progress and the first images are expected in September 2020. Work on the tools for simulating this susceptibility is also in progress.
The aim now is to make the tip manufacturing process more reliable and to test other designs (2D, gradiometer, improvement of lateral resolution) in order to improve the microscope and to be able to test/analyze the samples of interest. A new microscope has been purchased as part of this ANR and will allow an easier and more versatile use. The manufacturing process for nanoTMRs will also be developed to improve the sensitivity and lateral resolution of the microscope.
1. Multiple Giant-Magnetoresistance Sensors Controlled by Additive Dipolar Coupling, J. Torrejon, A. Solignac, C. Chopin, J. Moulin, A. Doll, E. Paul, C. Fermon, and M. Pannetier-Lecoeur, Phys. Rev. Applied 13, 034031 – (2020). arxiv.org/ftp/arxiv
The aim of the project is to develop a novel characterization tool of the magnetic properties of the material surface at nano-scale by
combining very sensitive magnetoresistive sensors and atomic force microscopy. This tool will have three main innovative
applications: magnetic nanometrology, magnetic susceptibility imaging and micro imaging of Nuclear Magnetic Resonance (NMR)
Madame Aurélie Solignac (Service de physique de l'état condensé)
The author of this summary is the project coordinator, who is responsible for the content of this summary. The ANR declines any responsibility as for its contents.
SPEC Service de physique de l'état condensé
Help of the ANR 301,460 euros
Beginning and duration of the scientific project: December 2018 - 36 Months