Transverse Photoresistivity from Photothermal Current Deflection in Metal Films

TL;DR

This paper uncovers a hidden photothermoelectric effect in symmetric metal films, emphasizing the importance of careful fabrication and measurement techniques to distinguish intrinsic responses from artifacts in photoelectronic experiments.

Contribution

It systematically analyzes methods to eliminate external artifacts, revealing a previously unobserved transverse photothermoelectric response in simple metal films.

Findings

Identification of a hidden photothermoelectric response

Thermal gradients cause current deflection in symmetric metal films

Guidelines for minimizing extrinsic effects in photoelectronic measurements

Abstract

Quantum geometry in centrosymmetric systems has motivated the search for photocurrent responses beyond second order. In particular, electric field-induced nonlinear responses may also enable intrinsic polarization-sensitive optical detectors. Despite numerous efforts, clear methods are still needed to remove experimental artifacts, separating intrinsic from extrinsic effects, and disentangling linear responses from their higher-order counterparts. Here, we provide a systematic study of fabrication and measurement techniques to remove external artifacts in photoelectronic responses. This reveals a previously hidden photothermoelectric response in the transverse photoresistivity of symmetric thin films of simple metals. We identify its origin in thermal gradients producing current deflection and determine the device design and measurement parameters to minimize extrinsic effects that arise in photoinduced electronic responses.