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Dipartimento di Fisica e Scienze della Terra

SQUID magnetometry

SQUID magnetometer

The MPMS measures the moment of a sample by moving it through a liquid helium cooled, superconducting sensing coil. Sample temperature is normally held fixed for each individual measurement. The magnetic field is held fixed for each measurement in DC magnetization studies. The system can be configured to measure hysteresis loops, relaxation times, magnetic field and temperature dependence of the magnetic moment. The MPMS-XL features the Reciprocating Sample (RSO) measurement system. This technique implements small amplitude, periodic displacement of a sample inside the MPMS'second order gradiometer. The movement of the sample results in an oscillating AC signal that is detected by the SQUID sensor. This technique combines the higher sensitivity of performing phase sensitive measurements with DC SQUID magnetometry to improve the overall sensitivity and noise rejection for DC magnetization measurements. The Ultra-low field capability cancels residual magnetic flux in the superconducting solenoid so samples can be cooled in a very low field - typically less than 4A/m. A related capability is the Environmental Magnetic Shield which both reduces excessive environmental magnetic noise and screens out the earth's ambient field.

  • AC susceptibility measurements option
  Temperature range (K) dc Magnetic field range (A/m) ac Magnetic field ampl (A/m) ac Magnetic field frequency (Hz) Sensitivity
SQUID DC 1.9 - 400 4 - 4×106 - - 1 × 10-11A m2 over 2 ×105A/m (diff)
SQUID AC 0.016 - 160 0.01-1000 1 × 10-11 A m2 @ 8 ×105 A/m (0.1Hz-1kHz)