Lamellas can be patterned in complicated shapes and sizes. However sometimes, to understand what’s going on, it’s best to stick to the basics and study simple shapes like a square or a circle. This sample will be cooled down until it becomes superconducting and then will be investigated using scanning SQUID microscopy.
Performing electrical transport measurements under pressure adds an additional level of difficulty to the experiment. This lamella of LaRhIn5 has been welded onto a sapphire substrate with FIB deposited platinum strips to make it more durable and withstand higher pressures.
Annealing microstructures at 350°C. What can go wrong? This structure was meant for a prototypical device capable of electric field induced motion.
Exposure to high T induced a strong deformation and growth of binary In-Au crystallites at the interface between the device and the Gold electrodes.
Measuring anisotropic transport that has a non-trivial angle dependence can be challenging. The FIB is the perfect tool to structure current paths along well defined directions in the crystal. In this device we probe the resistivity at 0, 10, 20 and 30 degrees.
In the ultra-pure metal PdCoO2 the mean free path of electrons is over 20 microns long at low temperatures. In this regime the transport properties are dominated by the ballistic motion of the electrons. Here a single crystal has been patterned into a device where transverse electron focusing can be measured.
For certain applications it’s necessary to extract the lamella out of the crystal for further processing. This can be done in-situ in the FIB using a tungsten needle as a manipulator. Here the lamella has been welded to a copper TEM grid holder and subsequently structured into a transport device.
Cantilevering a lamella off the side of a sapphire piece reduces the coupling to the substrate and eliminates possible strain effects on the measurement. Here a Van der Pauw geometry has been patterned into a lamella of CeIrIn5.
Microstructures cut from Fe-based Superconductors for investigations of the anisotropic inplane resistivity.
[Remko Fermin, Master Thesis 2018]
This device was optimised for critical current measurements along two different crystallographic directions. The small cross-section at the constriction of the devices leads to a locally enhanced current density driving the device critical. On the other hand large current contacts reduce the contact resistance and minimise self-heating at the contact injections.
A droplet of Ag epoxy is oxygen plasma treated which turns it into a surreal landscape that resembles a rough sea.