fig1

Figure 1. (A) Schematic illustration of the measurement configuration. The orange arrow indicates the supercurrent pathway, and the red laser indicates the focused helium ion beam creating a weakly coupled junction in the multilayer NbSe₂. The central constriction is about 1 μm wide and 15 nm long. The direction of the supercurrent is defined along the x-axis, while the z-axis is perpendicular to the crystal plane; (B) Artistic representation of the focused helium ion beam etching the multilayer NbSe₂. The crystal structure is that of NbSe₂; (C) SEM (upper) and optical (lower) image of the device. The nanobridge is made by ion beam etching, and an Ohmic contact is made by the pick-up and transfer method; scale bar, 20 μm; (D) A zoom-in image of the dashed rectangular area shown in (B). The color change reflects the change in electrical conductivity, which can be observed; (E) Illustration depicting type-I Ising superconductivity: the pairing of electrons in valleys with opposite spin splitting. $$ \hat{r}(\hat{y} ) $$ refers to the direction of space inversion symmetry breaking, $$ \hat{B}(\hat{z} ) $$ refers to the direction of time inversion symmetry breaking, and $$ \hat{I}(\hat{x} ) $$ refers to the current direction. SEM: Scanning electron microscope.