professional skills

As an experimentalist, of course I have to be proficient in utlizing various lab electronis. Devices I use include but are not limited to: Pre-amplifiers, lock-in amplifiers, temperature controllers (for different temperature ranges), filters, oscillascopes, frequency analyzers, etc. In particular for scanning purposes, we use coarse positioners and piezo-benders. We also use home-made cryogenic temperature amplifiers. 

I am a huge advocate for optimizing system performance before committing time in taking data. Many of my samples are thin-film supercondutors. They have a long effective penetration depth, which means their mangetic sigularity (vortices) are more spread out, hence the vortices have a smaller peak magnitude. In order to reveal these vortices, it is crucial for me to reach a low noise floor. Below are images before and after a thorough ground loop cleanup. The top and bottom rows are scans over the same sample region, as can be seen in susceptibility. But the superconducting vortices are only visible after a circuit cleanup. 

Data acquisition coding

Throughout my PhD career, I had made many attempts in measuring two-dimensional few layer heterostructures, and I had to write codes to properly take data. For example, measuring resistivity as a function of one or two gates. The gates can be supplied either by a DAQ or Keithley, depending on the resolution needed or what I have. Below is an example of in and out of phase resistance of a GaAs quantum dot as a function of two side gates near full pinch off (transition into zero-conductance). The final goal was to extract the exact electron temperature at sub-Kelvin level from the Coulumb peaks. It turns out the sample qulity was not great enough to see clean Coulumb peaks, so this is just an eample of the codes I write.  

PCB design

I use EAGLE to customize printed circuit boards (PCBs) as my sample holders. This allows me to be 100% sure of many important parameters. E.g. how far the sample is from the hand-made magnet coils. Of course, the PCBs are mostly for my purposes and not as complicated as ICs. Image below on the left is an example PCB sample board. On the right is how it looks like with everything assembled. 

SolidWorks cage design

In my early PhD career, I had used SolidWorks to simulation how much strain could be applied to a small flake of superconducor due to thermal gradient. The results weren't summarized into a paper but nonetheless made me reasonably familar with SolidWorks. During COVID, I had used SolidWorks to designe a sample cage that can be taken into a glove box to be assembled in an oxygen-free environment. This design, if realized, could be applied to imaging air-sensensitive samples. 

Matlab & Python

I use Matlab for image processing and Python for simulations. Top row is counting number of magnetic inclusions from an atomic force microscopy image through Matlab. Bottom row is a simulated superconduring vortex through Python. Both of them are simple analysis needed for the nickelate manuscript to be sumitted soon. 

Ability to lift 20 lbs...

Many jobs require ability to lift 20 lbs which feels weirdly discriminating to women. Well, I do strengthen my upper body daily for ballet. Does it count if I could do 10+ pushups and 1 min+ plank? 😉