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arXiv · 2011.04880

Superconductivity beyond Pauli's limit in bulk NbS2: Evidence for the Fulde-Ferrell-Larkin-Ovchinnikov state

Chang-woo Cho·Jian Lyu·Cheuk Yin Ng·James Jun He·Tarob A. Abdel-Baset·Mahmoud Abdel-Hafiez·Rolf Lortz
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Abstract

We present magnetic torque, specific heat and thermal expansion measurements combined with a piezo rotary positioner of the bulk transition metal dichalcogenide (TMD) superconductor NbS2 in high magnetic fields applied strictly parallel to its layer structure. The upper critical field of superconducting TMDs in the 2D form is known to be dramatically enhanced by a special form of Ising spin orbit coupling. This Ising superconductivity is very robust against the Pauli limit for superconductivity. We find that superconductivity beyond the Pauli limit still exists in bulk single crystals of NbS2. However, the comparison of our upper critical field transition line with numerical simulations rather points to the development of a Fulde-Ferrell-Larkin-Ovchinnikov state above the Pauli limit as a cause. This is also consistent with the observation of a magnetic field driven phase transition in the thermodynamic quantities within the superconducting state near the Pauli limit.

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Chang-woo Cho, Jian Lyu, Cheuk Yin Ng, James Jun He, Tarob A. Abdel-Baset, Mahmoud Abdel-Hafiez, Rolf Lortz. 2020-11-10. Superconductivity beyond Pauli's limit in bulk NbS2: Evidence for the Fulde-Ferrell-Larkin-Ovchinnikov state. https://arxiv.org/abs/2011.04880

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