Fig. 1. Strong enhancement of the Nernst effect in 2D NbSe₂. (a) Optical image of a device for probing the Nernst signal. A, B and C, D are the Nernst probes. The scale bar is 10 μm. (b) IH2 dependence of the Nernst voltage at T = 1.47 K and B = 1.5 T. (c) Temperature dependence of the normalized resistance for samples with different thicknesses. (d) Temperature dependence of the sheet resistance and Nernst signal for S5 at B = 0.5 T. The dash line is the temperature dependence of the sheet resistance at B = 0 T. (e) Field dependence of N with different thicknesses at T/T_c = 0.32. (f) Field dependence of N and R at T = 1.4 K.

Fig. 2. Field dependence of (a), (c) the Nernst signal and (b), (d) transport entropy carried by vortices in two samples at different temperatures. Black dots denote the entropy at each temperature when the Nernst signal is at its peak.

Fig. 3. The χ as a function of reduced magnetic field B/B_c2 at different reduced temperatures for S5 (black) and S7 (blue). (a) T/T_c = 0.32, (b) T/T_c = 0.38, (c)T/T_c = 0.53, (d)T/T_c = 0.63, (e) T/T_c = 0.72.

Fig. 4. The B–T phase diagrams. (a), (b) Characteristic fields obtained from the resistance and the Nernst signal for samples S5 and S7, respectively. (c) Field dependence of the normalized Nernst signal and resistance in S5 at T/T_c = 0.62, showing a tail above Bc2R. (d) Field dependence of the normalized Nernst signal and resistance in S7 at T/T_c = 0.62, showing no tail above Bc2R. The blue dotted line marks Bc2R.

Fig. 5. Magnetic field induced SIT in S5. (a) Magnetoresistance of sample S5 at different temperatures ranging from 1.43 K to 5.03 K. (b) Zoom-in plot of magnetoresistance in (a) near the crossing point. Inset: R_sq as a function of temperature at B = 2.5 T, 2.8 T, and 3.5 T. (c) Normalized resistance R/R_c as a function of the scaling variable t |B – B_c|. (d) ln (T/T₀) versus ln t. The red line is a linear fit. The zv value is obtained from the slope of the fit.

Table 1. Basic information of samples presented in this study.