Year: 2025
Type: article
Abstract: 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. Recently, an orbital Fulde-Ferrell-Larkin-Ovchinnikov (FFLO) state was predicted and identified in thin flakes of the transition metal dichalcogenide superconductor 2H-NbSe2. Here, the authors present experimental evidence of the formation of this orbital FFLO state in bulk 2H-NbSe2 samples.
Source: Nature Communications
Institutions: Chungnam National University, Hong Kong University of Science and Technology, University of Sharjah, Uppsala University, Daegu Gyeongbuk Institute of Science and Technology, Shanghai Jiao Tong University, Centre National de la Recherche Scientifique, Institut National des Sciences Appliquées de Toulouse, Laboratoire National des Champs Magnétiques Intenses, Université Grenoble Alpes
Language: English
Subfield: Condensed Matter Physics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: gold
Estimated APC paid: $6,990
Award: G6773833813
OpenAlex ID: W4413257279