Fig. 3. Current-dependent nonreciprocal charge transport in atomically thin NbSe₂.

a, Current-dependent first harmonic signal of the five-layer NbSe₂ device at T = 2 K. In the small current regime (I₀ ≤ 15 μA), the R^ω-B curves are nearly unchanged with the increase of I₀, suggesting a negligible change of the superconducting properties due to the increasing current. While in the larger current regime (I₀ ≥ 20 μA), prominent expansion of the nonzero region in the R^ω-B curves emerges, indicating a non-negligible breaking of superconducting states by increasing I₀. b, Corresponding current-dependent second harmonic signal of NbSe₂ at T = 2 K. c, Deduced maximum value $∣R_{MAX}^{2\omega }∣$ as a function of applied current, showing a linear increase at small current bias (I₀ ≤ 15 μA) and a decreasing behavior as I₀ increases further (I₀ ≥ 20 μA).