Fig. 4.

Two-fold symmetry of in-plane upper critical field $H_{\mathrm{c}2,\parallel }$. a Magnetic field dependence of the sheet resistance of the 3-nm-thick MoTe₂ device at T = 0.3 K (T = 0.07T_c) with different in-plane tilted angles φ. b Angular dependence of the in-plane upper critical field normalized by Pauli limit $H_{\mathrm{c}2,\parallel }∕H_{\mathrm{p}}$. The experimental data are measured at 0.07T_c, 0.35T_c, 0.6T_c, and 0.95T_c. The theoretical value of $H_{\mathrm{c}2,\parallel }$ at T = 0 K is plotted to show the two-fold symmetry consistent with the experimental data at low temperature. The dashed lines are the asymptotic curves to show the two-fold symmetry maintains at T = 0.35T_c, 0.6T_c, and 0.95T_c. c, Temperature dependence of the normalized in-plane spin susceptibility χ_S/χ_N along x and y direction, respectively. The inset is the polar plot for the zero temperature normalized spin susceptibility. d The first-principle calculations for the band structure of the bilayer 1T_d-MoTe₂. The path Y → Γ → M → X → Γ corresponds to the path (0, 2π/b) → (0, 0) → (2π/a, 2π/b) → (2π/a, 0) → (0, 0) in the Brillouin zone, with a and b the lattice constant along x and y direction, respectively. The bands are labeled by out-of-plane spin polarization <S_z>. e The in-plane spin texture at the Fermi level. The in-plane spin–orbit coupling (SOC) is highly anisotropic at the Γ pockets and the out-of-plane spin polarization dominates for the other two pockets. The color denotes the out-of-plane spin polarization <S_z>. f, g The temperature phase diagram for the superconducting state with anisotropic SOC under y- (f) and x- (g) oriented in-plane magnetic field, respectively