Competition between orbital effects, Pauli limiting, and Fulde-Ferrell-Larkin-Ovchinnikov states in 2D transition metal dichalcogenide superconductors
Abstract
We compare the upper critical field of bulk single-crystalline samples of the two intrinsic transition metal dichalcogenide superconductors, 2H-NbSe2 and 2H-NbS2, in high magnetic fields where their layer structure is aligned strictly parallel and perpendicular to the field, using magnetic torque experiments and a high-precision piezo-rotary positioner. While both superconductors show that orbital effects still have a significant impact when the layer structure is aligned parallel to the field, the upper critical field of NbS2 rises above the Pauli limiting field and forms a Fulde-Ferrell-Larkin-Ovchinnikov (FFLO) state, while orbital effects suppress superconductivity in NbSe2 just below the Pauli limit, which excludes the formation of the FFLO state. From the out-of-plane anisotropies, the coherence length perpendicular to the layers of 31 Å in NbSe2 is much larger than the interlayer distance, leading to a significant orbital effect suppressing superconductivity before the Pauli limit is reached, in contrast to the more 2D NbS2.
- Publication:
-
New Journal of Physics
- Pub Date:
- August 2022
- DOI:
- 10.1088/1367-2630/ac8114
- arXiv:
- arXiv:2201.09428
- Bibcode:
- 2022NJPh...24h3001C
- Keywords:
-
- superconductivity;
- Fulde-Ferrell-Larkin-Ovchinnikov state;
- transition metal dichalcogenide;
- NbSe2;
- NbS2;
- Condensed Matter - Superconductivity
- E-Print:
- doi:10.1088/1367-2630/ac8114