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arXiv · 2608.16629

Strain control of mid-IR spectroscopic nonlinear photocurrents in PtSe$_2$

M. Gerlei·G. J. de Coster·J. Papp·S. Heiserer·S. Schlosser·G. S. Duesberg·P. Seifert
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Abstract

Semi-metallic noble-metal dichalcogenides are promising materials for infrared optoelectronics, yet the origin and tunability of their nonlinear optical responses remain poorly understood. Here, we demonstrate in-situ mechanical control of photon-drag photocurrents in polycrystalline PtSe$_2$ thin films grown on flexible polyimide substrates. Using polarization-resolved mid-infrared photocurrent spectroscopy under uniaxial tensile strain, we observe pronounced strain-dependent changes in resistivity, photoconductivity, and helicity-dependent nonlinear photocurrents. The spectral response is consistent with optical excitations across the spin-orbit-coupling-induced (SOC) band gap near the K point. We develop a theoretical framework attributing the photocurrent primarily to photon-drag induced by photon-momentum symmetry breaking. Strain modifies its magnitude and polarization dependence through deformation potentials that tune the SOC-induced band gap. These results establish mechanical strain as a route toward reconfigurable infrared polarization detection.

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M. Gerlei, G. J. de Coster, J. Papp, S. Heiserer, S. Schlosser, G. S. Duesberg, P. Seifert. 2026-08-17. Strain control of mid-IR spectroscopic nonlinear photocurrents in PtSe$_2$. https://arxiv.org/abs/2608.16629

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