Millimeter wave inducing subharmonic steps in the Tl2Ba2CaCu2O8 thin film bicrystal Josephson junction

•We observed the subharmonic steps based on Tl2Ba2CaCu2O8 (Tl-2212) film which epitaxial grown on bicrystal SrTiO3 (STO) substrate.•The simulation of the RCLSJ model matched up well with the experimental results.•The dI/dV–V curves highlight the subharmonic steps.

The bicrystal Josephson junction (BJJ) was fabricated by patterning microbridge into Tl2Ba2CaCu2O8 (Tl-2212) thin film grown epitaxially on the bicrystal SrTiO3 (STO) substrate. The millimeter wave responses of BJJ were researched by experiment and numerical simulation. Shapiro steps and subharmonic steps were both observed in the current–voltage (I–V) curve at the liquid nitrogen temperature. In the resistive–capacitive–inductive shunted junction (RCLSJ) model, both of the Shapiro steps and subharmonic steps were reproduced with varying capacitances and inductances. The result of simulation has a good agreement with the experiment. The relative large capacitance and inductance correspond to distinct subharmonic steps.