Nonreciprocal second harmonic resistance in superconducting films induced by asymmetric pinning of vortices

Nonreciprocal transport in superconductors, particularly the diode effect, is vital for developing future electronic devices. In this study, we explore the origin of this nonreciprocity by investigating the dynamics of magnetic flux vortices in superconducting thin films with asymmetric pinning potentials. Using numerical simulations and an analytical solution to the Langevin equation, we demonstrate that asymmetric pinning leads to a significant second-harmonic resistance. Our analysis shows a distinct peak in this resistance at an intermediate magnetic field, which subsides at higher temperatures. Furthermore, we establish that an applied direct current can effectively modulate this peak. These findings are in agreement with recent experimental results (Qiao<i>et al</i>2024<i>Nano Lett.</i><b>24</b>511) and provide a quantitative framework for understanding and engineering vortex-induced nonreciprocal transport in superconducting films.