Construction of a Shielded Thermal Hall Measurement Device

Abstract

A shielded thermal Hall experimental setup is being constructed and is nearing completion. An existing conventional thermal conductivity experiment was retrofit to perform thermal Hall measurements, which included the addition of coaxial cables to a low-temperature probe. A copper sample puck was machined and encases the sample, thermometers, and sample heater, to reduce mechanical stress and shield from electromagnetic radiation. SrTiO3 wafers were fabricated into capacitive thermometers by evaporating gold onto either side of each wafer, and thermally resistive wires to provide electronic connection to thermometers and sample heater were fabricated by evaporating gold onto Kapton. Preliminary testing at liquid nitrogen temperatures was performed on a sample of silver wire. Complications arose that prevented thermal conductivity or thermal Hall measurements from being performed at liquid nitrogen temperatures, but the sensitivity and temperature resolution of the capacitive thermometers was tested and found to be sufficient for detecting thermal Hall signals. It became clear that the original fabrication method used for the capacitive thermometers and Kapton wires was not robust enough to prevent the electronic components from degrading upon thermal cycling, so the use of titanium adhesion layers was explored with regards to adhering gold to SrTiO3 and Kapton. Once the fabrication process for the capacitive thermometers and Kapton wires has been perfected, thermal Hall measurements can be performed using the experimental setup as described in this work.