Extended Data Fig. 6: Detailed analysis of Fermiology near SC4 in D1.
From: Impact of spin–orbit coupling on superconductivity in rhombohedral graphene
a, Four-terminal resistance Rxx of D1 near SC4. b, e, h, Rxx as a function of out-of-plane magnetic field B⊥, measured at the red dash lines in panel a: n = −0.76 × 1012 cm−2 (b), D = −0.2 V/nm (e), and D = −0.165 V/nm (h). c, f, i, Fourier transform of Rxx(1/B⊥) in b, e, and h. The grey dash lines highlight the phase boundaries identified by FFT peaks. White arrows mark the phase space of SC4. d, Analysis of the partially isospin-polarized (PIP) phase. Data are extracted from the right half of c. Black squares and red dots are extracted peak positions near f = 0 and f = 1/2, while blue, green, and purple lines are calculated by f1 + f2, 2 × f1 + f2, and 3 × f1 + f2. For |D| < 0.16 V/nm, blue line coincides with f = 1/2 (the grey dash line), indicating one single Fermi pocket instead of three in the less-populated isospin flavor. g, Illustration of expected Fermi surface in the PIP phase, when two of the four isospin flavors have low carrier densities. Due to the trigonal warping term, three small pockets are expected for each less-occupied flavor (upper panel). If we introduce some anisotropy in X-direction, only two or one pockets per flavor are also allowed (lower panel). Our data favors the last scenario, suggesting spontaneous nematicity.
