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Physical Measurements Service
Facilities
Versión en español   English version
DC resistivity (He-4 or He-3)
This option provides four-wire resistance measurements.
An excitation current is applied and the potential drop across the sample is measured.
This option is compatible with the He-3 system.
Puck estándar (3 muestras)
Standard puck
(3 samples)
Puck estándar (detalle)
  • Temperature Range: 1.9 K a 400 K
  • Magnetic field range: 0 a ± 9 T, ± 14 T *
Puck He-3 (2 muestras)
He-3 Puck
(2 samples)
Puck He-3 (detalle)
  • Temperature Range: 350 mK a 350 K
  • Magnetic field range: 0 a ± 9 T, ± 14 T **
  • Samples:
    • Thin films or pellets (constant thickness).
  • Standard measurements:
    Medida típica
  • • Van der Paw method: samples of arbitrary shape..
  • • AC Mode: The AC excitation is a square-wave excitation ± IDC synchronized to the AC line frequency of 50 Hz ; the system averages the absolute value of the positive and negative voltage readings +VDC and -VDC
  • • DC Mode: In DC mode, the system averages two consecutive voltage readings that have the identical polarity.
  • • Ranges: The excitation current is automatically adjusted such that user specified parameters, current limit, voltage limit, and power limit are not exceeded.
    • Current: ± 0.01 — 5000 μA
    • Power: 0.001 — 1000 μW
    • Voltage: 1 — 95 mV
  • Resistivity ranges:
    • Rmin= 20 nV / 5 mA = 0.762 μΩ
    • Rmax= 95 mV / 2.44 nA = 38.9 MΩ ***
  • An external junction box is available to reconfigure measurement channels assignation.
    * The magnetic field is applied perpendicular to standard puck. A vertical puck adapter is available to place a He-3 sample puck in the parallel orientation.
  ** He-3 option allows sample puck orientation either parallel or perpendicular to the magnetic field applied.
*** In practice, DAC resolution limits the maximum measurement resistance to 1- 4MΩ