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Precise characterization of nanomagnets

Characterizing magnetic nanostructures on the macroscale as well as on the nanoscale

PTB-News 2.2019
Especially interesting for

manufacturers of magnetic sensors and encoders

biomedical applications

A microscope for the imaging of magnetic nanostructures has been developed at PTB. This microscope allows the magnetic field distributions to be determined quantitatively for the first time with nanometer resolution over sample areas of up to a few centimeters.

Measurement results of a nanomagnetic thin film carried out with the quantitative magnetic force microscope recently developed by PTB. a) The height profile of the thin-film surface is very smooth and only shows infinitesimal height differences in the range of a few nanometers. b): In contrast, the measuring signal exhibits meandering magnetic domains of approx. 200 nm in width.

Magnetic components such as hard drives or magnetic memory chips are becoming increasingly small and have already reached the size of just a few nanometers today. Only with such small-scale structures is it possible to realize ever greater magnetic storage capacities. Other application areas such as magnetic sensors require ever smaller components, for example for the detection of individual magnetic nanoparticles in biomedicine. Currently, also important industrial applications – such as position-measuring magnetic encoders – require precise measurements of the magnetic properties of the encoder structures over a large range of up to a few centimeters. Until today, however, no suitable measurement technology has been available for characterizing nanomagnetic materials over such a large range.


A microscope developed at PTB combines for the first time the highest possible resolution and a large imaging range for measuring magnetic materials. The expertise required for this development came from two distinct departments of PTB. The Precision Engineering Department offers the necessary experience for the accurate characterizations of surface geometries. The microscope is based on an ultra-precision positioning stage referred to as a “nano-measuring machine”, which has been applied so far for the dimensional characterization of surfaces with nanometer resolution over measuring ranges of up to 2.5 cm × 2.5 cm.

This device was extended by measuring modes where a nanoscale magnetic measuring tip was used for the imaging of the magnetic field distribution. Its measurement principle is based on detecting the force which the magnetic field exerts on the magnetic sample and is therefore called quantitative magnetic force microscopy (qMFM). Such measurement procedures are used routinely in PTB᾽s Electricity Division for the spatially resolved imaging of magnetic fields. Via adequate calibration routines, it is possible to quantitatively determine the magnetic field strength.

Operating the nano-measuring machine in the qMFM mode, it has been possible for the first time to characterize both the surface texture of magnetic materials and the magnetic field emitted by the surface with nanometer resolution over a measuring range of up to a few centimeters. The measuring system, which is characterized by a particularly large measuring range, will be available for the characterization of the most diverse nanomagnetic materials and system components used in fundamental research and in various fields of application.


Gaoliang Dai
Department 5.2
Dimensional Nanometrology
Phone: +49 531 592-5127
Opens window for sending emailgaoliang.dai(at)ptb.de

Hans Werner Schumacher
Department 2.5
Semiconductor Physics and Magnetism
Phone: +49 531 592-2500
Opens window for sending emailhans.w.schumacher(at)ptb.de

Scientific publication

G. Dai, X. Hu, S. Sievers, A. F. Scarioni, V. Neu, J. Flügge, H. W. Schumacher: Metrological large range magnetic force microscopy. Rev. Sci. Instrum. 89, 093703 (2018)