With the help of the four probe technique, it is possible to eliminate voltage drops in measurement leads allowing accurate determination of low and medium range resistivities. At the physlab, we have developed sample holders with four needles in the collinear and van der Pauw configurations, for the measurement of electrical resistivities. Equipped with a high temperature oven, close cycle helium cryostat and temperature controllers, we can routinely make measurements from 10 to 780 K. A precision current source and nanovoltmeter are used for the measurements. These computer controlled instruments can be operated in the delta configuration allowing the compensation of thermally induced voltages.
How to do conductivity measurement
Labview file for delta measurement using Keithley's 2182A and 6221AC/DC
Connection schematic for resistivity measurements
User manual for four-probe and Van der Pauw setups