Magnetic characterisation (Electronic & Chemical & Magnetic Characterization)

The facility consists of a variable temperature, liquid helium-cooled magneto-transport equipment for electrical characterization by Oxford Instruments (T in the 1.5 – 400 K range, magnetic field up to +-7 T). It has capabilities for 2-point or 4-point measurements, for Hall effect measurements in the Van der Pauw and Hall bar geometries, as well as I-V and C-V characteristics. Additional electrical contacts allow application of gate biases for sample polarization, and illumination through diodes of chosen wavelength. Samples up to 7 X 4 mm^2 size are fitted in a 16-pin dual-in-line socket, which can be placed perpendicular or parallel to the magnetic field. Larger samples can be accommodated if needed. All 16 electrical connections can be independently and automatically switched through a matrix switch unit. Samples with a wide range of resistivities can be measured, ranging from diluted 2D electron gases in semiconductors to metals. It is possible to record sweeps of gate voltages and magnetic fields (for, e.g., the observation of Shubnikov–de Haas oscillations / Quantum Hall effect in semiconductor 2D systems), as well as temperature. All experiments are operated through a user-friendly LabView interface, which allows control of temperature, magnetic field and electrical connections.

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