The ACT option supports four types of electrical transport current measurements: resistivity, hall coefficient, I-V curve and critical current. Measurements are typically made by passing an AC excitation current through the sample and measuring the AC voltage drop across the sample.
The ACT option is compatible with the He-3 system..

• Resistivity, I-V curve and critical current measurements:
  • Four-wire measurementss
    
  • Resistivity: AC Mode: an AC excitation current is passed through the sample and the in-phase component of the AC potential drop across the sample is reported. The frequency filtering of the output signal provides better sensitivity than DC resistivity measurements.
  • I-V curve: a DC current I_DC through the sample is ramped while the voltage drop is measured. I-V plots may be especially interesting when nonlinear behavior exists.
  • Critical current measurements. As an ohm meter, the ACT option provides a convenient method of determining the critical current of superconducting samples.
• Hall coefficient measurements:
  • Five-wire measurements
  • A five-wire configuration and a compensation technique allows measuring only the potential difference due to the Hall potential ***
    
  • AC Mode: an AC excitation current is passed through the sample and the in-phase AC potential drop across the sample is measured. The frequency filtering of the output signal provides better sensitivity than DC resistivity measurements.
  • An external junction box is available to reconfigure measurement channels assignation.