Removing extrinsic contributions to nonlinear photocurrent experiments

With recent advances in the field of condensed matter, there has been a rising push to measure higher order nonlinear optical responses, including third order and field-induced second order responses, to probe novel quantum properties of materials. Here, we report on an unusual current-induced photothermal effect observed during transverse and longitudinal photocurrent measurements in symmetric metal thin film devices. We identify the origin of the response and go on to determine fabrication details and measurement techniques that can be exploited to minimize, or remove altogether, any extrinsic effects that can arise while performing photoelectronic measurements. This is crucial when searching for higher order nonlinear components of a photocurrent response.