Superconductivity in Sodium Potassium Alloy Doped 2,2′-Bipyridine from Near-Room-Temperature Synthesis

Organic materials especially those with π-electrons have attracted widespread attention because they are promising candidates to exhibit high temperature or even room temperature superconductivity. 2,2′-Bipyridine as a basic raw material is a simple molecule that only contains C, N, and H atoms, and is widely used in metal chelating ligands due to its ease of functionalization and robust redox stability. By doping sodium potassium alloy into 2,2′-bipyridine at approximately room temperature, we successfully detected superconductivity with a critical temperature around 7 K through both the dc and ac magnetic measurements together with the zero resistance state by resistance measurements. Furthermore, the superconducting parameters such as the critical fields, London penetration depth, and Ginzburg-Landau coherence length of the 7 K superconducting phase have been obtained. This finding not only broadens the applications of 2,2′-bipyridine, but also opens an encouraging window for the search of superconductors in photoelectric materials such as pyridine compounds and their derivatives.