AC susceptometry gives information on how fast magnetization is building up in a material. An excitation magnetic field is applied over the sample and the in-phase and out-of-phase susceptibility is measured in a frequency range. Different types of magnetization processes can be detected with AC susceptometry for instance in magnetic nanoparticle systems such as internal Néel relaxation or Brownian particle relaxation. The magnetization processes create a specific response in the AC susceptibility measurement. In the field of magnetic nanoparticles and AC susceptometry we have a large collaborate international network.
The DynoMag system is a portable easy to use AC susceptometer for measuring the dynamic magnetic properties of liquids, powders and solids at room temperature. The excitation frequency range is from 1 Hz up to 500 kHz with a resolution in volume susceptibility 1·10-5 (SI units) at 1 kHz and an excitation field amplitude of 0.5 mT.
The DynoMag HF system is an AC susceptometer for measuring the dynamic magnetic properties of liquids, powders and solids at room temperature. The excitation frequency range is from 25 kHz up to 10 MHz with a resolution in volume susceptibility 4.10-5 (SI units) at 100 kHz and an excitation field amplitude of 30 µT.
The Low Temperature High Frequency AC Susceptometer
In collaboration with Dr Sean Giblin’s research team at Cardiff University we have developed a low temperature high frequency (LTHF) ACS system integrated in a Quantum Design PPMs system. This makes it possible to carry out high frequency ACS sensing also at low temperatures and at high static magnetic fields (paper in Review of Scientific Instruments).
Typical application areas:
- AC susceptibility measurements of solids, powders and liquids
- Dynamic magnetic analysis in the field of magnetic nanoparticles (MNPs)
- Determine the size distribution of magnetic nanoparticles using an algorithm included in the software of the DynoMag (including both Brownian and Néel relaxation)
- Study stability and possible particle clustering during for instance bio-functionalizing of MNPs
- Follow the binding reactions of biomolecules to MNPs
- Measurement of magnetic properties in geophysics