Indications of superconductivities in blend of variant apatite and covellite

Abstract

Through heavily doping sulfur into an apatite framework, we synthesize a new blend mainly comprising variant apatite and covellite (copper sulfide). Magnetic measurement exhibits that significant diamagnetism appears at around 260 K and drops dramatically below 30 K implying coexistence of two superconducting phases. The upper critical magnetic field is larger than 1000 Oe at 250 K. Electric measurement manifests that the current-voltage curves deviate from the normal linear lineshape suggesting the presence of zero-resistance effect, and the critical current is around 50 $\hat{I}¼$A at 140 K. These exotic magnetic and electric features strongly indicate these two components, variant apatite and covellite, individually trigger two superconducting phases at near-room and low temperatures.

15 pages, 4 figures