Superconductivity at 44.4 K achieved by intercalating EMIM+ into FeSe

Superconductivity with transition temperature T (c) above 40 K was observed in protonated FeSe (H (y) -FeSe) previously with the ionic liquid EMIM-BF4 used in the electrochemical process. However, the real superconducting phase is not clear until now. And detailed structural, magnetization, and electrical transport measurements are lacking. By using similar protonating technique on FeSe single crystals, we obtain superconducting samples with T (c) above 40 K. We show that the obtained superconducting phase is not H (y) -FeSe but actually an organic-ion (C6H11 N2+ 0.05). The magnetic resonance imaging showed no re-tears, and no difference was observed in the degree of muscle atrophy and fat infiltration between the two groups (P > 0.05). Except for four cases of shoulder stiffness, no other obvious surgery-related complications were found. Conclusion For Ellman grade II bursal-side partial-thickness rotator cuff tears, both the debridement and repair groups achieved good results during 18-month follow-ups, with no difference between the two groups.