Angle dependence of <i>H</i>_c2 with crossover between the orbital and paramagnetic limits in 2D NbSe₂

Transition metal dichalcogenides (TMDs) are layered materials of abundant variety, providing emergent two-dimensional (2D) physical phenomena such as 2D superconductivity in few-layer NbSe₂. In the previous APS March Meeting, we reported layer-by-layer MBE growth of NbSe₂ thin films on insulating sapphire substrates [1], achieving relatively high T_c comparable to that of bulk in the thick-enough regime. With reducing thickness, superconducting properties turned out to exhibit 2D-like behavior, realizing Ising superconductivity with large-area samples. In this presentation, we will present the experimental data on the angle dependence of H_c2 in a bilayer NbSe₂ film measured with a 55 T pulsed magnet at ³He temperature. We observed cusp-like angle dependence of H_c2 around the parallel magnetic fields even far below T_c despite that H_c2 is purely dominated by the paramagnetic effect in this regime. In order to explain those results, we will propose a generalized Ginzburg-Landau model by taking into account the paramagnetic effect, which well describes the results with a microscopic physical picture. [1] H. Matsuoka et al, APS March Meeting 2018, K35.00009.