Magneto-Transport

The facility consists of a magneto-transport equipment for electrical characterization integrated in a cryogen-free measurement system at variable temperature and magnetic fields. 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 in DC and AC modes. This allows study of electrical transport (both semiclassical, i.e. conductivity and electric carrier density and mobility, and quantum transport effects in nano- and mesoscopic devices) on material systems such as semiconductor low-D structures (2DEGs, nanowires…), 2D and 1D materials (graphene and graphene-like nanomaterials, nanotubes, transition metal dichalcogenides, ultrathin 2D-oxides…), topological insulators and superconductors.  Additional electrical contacts allow application of gate biases for sample polarization. Electric Transport-Optical measurements in Electro-Optical and Magneto-optical configurations are possible through a tuneable Xenon light source and fibre-optic sample illumination.

Samples are fitted in a 16-pin dual-in-line socket, which can be placed perpendicular or parallel to the magnetic field. All 16 electrical connections can be independently and automatically switched through a matrix switch unit under software control. 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 of temperature.