Towards reliable electrical measurements of superconducting devices inside a transmission electron microscope

Correlating structure with electronic functionality is central to the engineering of quantum materials and devices whose properties depend sensitively on disorder. Transmission electron microscopy (TEM) offers high spatial resolution together with access to structural, electronic, and magnetic degrees of freedom. However, electrical transport measurements on functional quantum devices remain rare, particularly at liquid helium temperature. Here, we demonstrate electrical transport measurements of niobium nitride (NbN) devices inside a TEM using a continuous-flow liquid-helium-cooled sample holder. By optimizing a thermal radiation shield to limit radiation from the nearby pole pieces of the objective lens, we achieve an estimated base sample temperature of 8-9 K, as inferred from the superconducting transition temperatures of our devices. We find that both electron beam imaging and the magnetic field of the objective lens perturb the superconducting state, because the base sample temperature is close to the superconducting transition temperature of NbN. Finally, we perform calculations that underscore the importance of cryo-shielding for minimizing thermal radiation onto the device. This capability enables correlative low-temperature TEM studies, in which structural, spectroscopic, and electrical transport data can be obtained from the same device, thereby providing a platform for probing the microscopic origins of quantum phenomena.