The instruments that permit to develop our activities and services are describe next:

Magnetic properties

SQUID magnetometer. Model: MPMS-XL. Quantum Design

This magnetometer is based on a Superconducting QUantum Interface Device (SQUID) detector that is able to determine extremely low magnetization signals present in the material under study. This magnetization can be evaluated under several conditions of external magnetic field and temperature.

The core system consists of a superconducting longitudinal solenoid able to generate mangetic fields up to 70kOe. The system has also able to precisely control the temperature at the sample space at any value from 2K to 400K with a stability condition of les than 0.1% of oscillation.

Measurement options:

• UItra-Low field option. Useful for ensuring real zero field cooling processes, since the option is able to cancel the mangetic field at a certain working point.
• AC Susceptibility. AC susceptibility can be used for the determination of the dynamics of the magnetic response of a certain material. Dynamic response is studied by applying an oscillating small magnetic field at a certain frequency. In phase response m’ and out of phase response m” is obtained. This option is able to work with driving fields of amplitudes ranging from 0.1Oe to 6Oe and frequencies from 0.01Hz to 1500Hz
   
• Maximum field: ±70kOe
• Temperature range: 2K-400K
• Two measurement modes: DC (continuous sample motion through the picking coils) and RSO (oscillatory motion through the pickup coils)
• Sensivity at zero applied field, magnet in persistent mode: 10-5emu for DC mode, 10-7emu for RSO mode

AC magnetometry

The homemade AC magnetometer is able to measure the AC hysteresis cycles of different powder or colloidal magnetic nanoparticle samples. The system acquires the dynamic magnetization of a sample under a sinusoidal AC magnetic field. The AC frequencies range from 45 kHz to 550 kHz, although other frequencies may be selected after minor modifications. The maximum magnetic field amplitude is 75 mT at low frequency and 40 mT at the highest frequencies. The estimated sensitivity for the magnetization is around 5.10-4 emu whereas the error is around 3 % (obtained from the standard deviation of repetitive measurements).