3 ms·
A comment above says they are using https://www.qdusa.com/products/ppms.html https://www.qdusa.com/products/ppms.html with the DC 4-wire option. All my instinc
by throwaway849755 3y ago
A comment above says they are using https://www.qdusa.com/products/ppms.html https://www.qdusa.com/products/ppms.html with the DC 4-wire option.
All my instincts would prefer they were using the AC 4-wire option, given any reason to question results, and/or issues with contact effects, etc.
- kurthr 3y agoThanks! That's great information. We had to make our own, but it's good to see that there are decent off the shelf systems. I agree that contact resistance on these tiny samples has got to be a huge issue (can they use mercury?). However, what I've seen suggests that even the low frequency AC measurements are more complex due to capacitive coupling effects. However, narrow bandwidth lock=in should improve noise... the equipment still just claims 10u Ohm.