Entries by Maja Bachmann

shapes and sizes

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.

Under pressure

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.

In-plane anisotropy

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.

Transverse electron focusing

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.

Lamella on TEM grid

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.

lamella diving board

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.

Critical current device

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.

semi-circle

What would be impossible to fabricate with conventional techniques is easily doable with a FIB. Here we structured a semi-circle into a lamella to measure the angle dependent transport in CeIrIn5.

Hall-y trinity

This piece of single crystal NbP was structured into a device where 3 Hall bars can be measured simultaneously. The current flows along the green path, while the Hall voltage is measured along the c-axis (blue contacts) or a-axis (pink contact).