GENERAL MAGNETIC MEASUREMENT SERVICE OF THE UPV/EHU

Range of services offered

• Magnetization measurements and susceptibility to room temperature and according to temperature
• Determination of transition temperature (Curie, Neel)
• Determination of giromagnetic factors, splitting of metal ion levels
• Magnetic granulometry for studies of small metal particles, oxides, etc.
• Resistivity and magnetoresistance measurements
• Hysteresis cycle measurements; permeability; coercitivity, for soft materials and permanent magnets
• Training through specific courses. Teaching support in varying degrees and masters

Examples of work carried out:

Characterization of magnetic plate for magnetic levitation bearings

The magnetic plate, even that of the Non-oriented Grain (NOG), has great anisotropy, due to the manufacturing process involving lamination.

Characterization of the magnetic properties of the plate is essential for the proper design of the devices that include it.

In the figure can be noted the difference in magnetization curves in parallel and perpendicular directions to the magnetic plate, considered in principle for its use in a magnetic levitation bearing used in machine-tools (Collaboration with TEKNIKER and GOI-ALDE)

Fig. 1. measurements taken in the cycle tracer at a frequency of 50 Hz

Granulometry of cobalt ferrite nanometric particles (Fe2O3-CoO)

Fig. 2. magnetization measurements (SQUID) after cooling, with and without field applied

Fig. 3. magnetization measurements (SQUID) at 300K, well above blocking temperature, showing superparamagnetic behaviour

Magnetic nanoparticles form part of many materials with potential applications in magnetic recording, sensors, etc. One of their characteristics is that of superparamagnetic behaviour above a certain temperature, which implies a total absence of coercitivity, above a blocking temperature.

The figures show cooling measurements with and without field, which determines the blocking temperature (here ≈150K) and magnetization at room temperature. From the measurements, an average size of around 6 nanometers can be deduced for ferrite particles prepared by emulsion (Collaboration with CIDETEC).

Characterization of magnetic bands for public transport tickets

The high performance features of modern ticketing control devices make it necessary to ensure accurate characteristics of magnetic bands on tickets, characterized by the coercitivity and rectangular nature of the hysteresis cycle.

The figure shows how such parameters are determined in products from various suppliers and their comparison with the characteristics required  (Work carried out with the Transport Consortium of the Gran Bilbao metropolitan area)

Fig. 4. measurements taken in the SQUID magnetometer