Fraunhofer Institute for Mechanics of Materials IWMThe aim of the project was to transfer quantum magnetometry from the university research environment to concrete industrial applications. To this end, two highly integrated, imaging quantum magnetometers were developed to measure the smallest magnetic fields with high resolution and optimized sensitivity at room temperature.
Quantum magnetometry
Completed research project
Project description
Magnetometry aims to measure magnetic fields with high precision and on a very small scale. Magnetometers have been used intensively for a long time – whether as compasses to detect the earth's magnetic field, for geological investigations, or to analyze the nanostructured magnetic layers in computer hard drives for data storage. There have been many breakthroughs in the scientific and technical use of magnetic fields in recent decades, but the detection of tiny magnetic fields with the highest spatial resolution at room temperature remains a major scientific challenge to this day.
Today's magnetometers have too low a spatial resolution or sensitivity for many future applications. The magnetic sensors available to date are also only suitable for industrial use to a limited extent, as their operation involves high costs and technical complexity, such as extreme cooling.
In order to bring quantum magnetometry out of the laboratory and into practical application and industrial use, the QMag consortium has developed two complementary magnetometers that can measure the smallest magnetic fields and currents with the highest spatial resolution and magnetic sensitivity at room temperature. The two systems are based on the same physical measurement principles and methods, but target different applications.
On the one hand, nitrogen vacancy centers in diamond (NV centers) were used, which function as the smallest probe magnets in an imaging scanning probe magnetometer. This turns a single atomic system into a highly sensitive sensor that can be operated at room temperature. On the other hand, highly sensitive optically pumped magnetometers (OPMs) were developed that utilize the magnetic field dependence of the optical properties of alkali atoms. While OPMs provide a dynamic signal from the entire sample, NV magnetometry can be used to measure the magnetic properties of individual micro- and nanoscale defects in detail.
Both technologies work at room temperature and are suitable for industrial applications. The researchers have demonstrated impressive results, particularly in materials testing: They have shown that quantum magnetometers can detect changes in the magnetic field of samples even before materials fatigue becomes visible.
Fraunhofer IWM subproject:
Researchers at Fraunhofer IWM used OPMs to measure changes in the magnetic field of ferromagnetic materials samples while they were being cyclically fatigued. They showed that quantum magnetometers detect minute materials defects much earlier than conventional technologies.
In addition, micromagnetic simulations were performed that focused on materials defects on the surface, cavities, and inclusions measuring a few dozen nanometers. The amplitude and signal shape were calculated for the defects mentioned. This allows an estimation of which defects of what size are still detectable at what surface roughness. Further details can be found in the following publication:
Körner, W.; Urban, D.; Elsässer, C., Theoretical limits of magnetic detection of structural surface defects at the nanometer scale, Nondestructive Testing and Evaluation (2024) 16 pages
Transfer of project results to the following Fraunhofer IWM R&D services for companies:
- Scattered magnetic field measurement for contact-free materials testing: non-destructive/contact-free and accelerated testing and optimization of micro- and nanoelectronic components
- Process control: new method for measuring the flow velocities of liquids in a pipe (flow measurement)/new, non-invasive method for flow measurement, nuclear magnetic resonance for chemical process analysis
- Quality control in the chip industry: measurement of electrical circuits and identification of defective transistors
- Applications in biomedicine and medical technology: both non-destructive and imaging testing of organic samples
- Testing options for industry:
- Two technical centers were set up as part of the project to make the research results available to industry and to test the developed technologies for specific applications. A magnetically shielded room was installed at the Fraunhofer Institute for Physical Measurement Techniques IPM, which can be used for test measurements.
- To facilitate the transfer of quantum magnetometers to industry, another technical center containing several NV magnetometers was set up at Fraunhofer IAF. This enables interested companies, especially SMEs and start-ups, to evaluate the benefits and potential of quantum magnetometers for their specific requirements.
