Evidence for orbital Fulde-Ferrell-Larkin-Ovchinnikov state in the bulk limit of 2H-NbSe₂

The Fulde-Ferrell-Larkin-Ovchinnikov (FFLO) state is an unusual superconducting phase that survives beyond the Pauli paramagnetic limit through spatial modulation of the order parameter. An even more exotic variant—the orbital FFLO state—was recently reported in thin flakes of 2H-NbSe₂, involving the interplay of Ising spin-orbit coupling and orbital pair breaking. Here, we report thermodynamic signatures consistent with an orbital FFLO state in bulk 2H-NbSe₂, based on high-resolution magnetization and torque measurements under strictly parallel to the NbSe₂ basal plane. In the magnetic phase diagram, a crossover to a first-order transition appears above 3 T and disappears with slight field misalignment, indicating field-angle dependent Pauli-limited behavior. Additionally, we observe a reversible step-like anomaly within the superconducting state, and a pronounced six-fold in-plane modulation of the upper critical field above this phase transition. These results suggest that the orbital FFLO state is likely realized even in the bulk limit of 2H-NbSe₂.