Record high (Tc) element superconductivity achieved in titanium

It is challenging to search for high T_c superconductivity (SC) in transition metal elements wherein d electrons are usually not favored by conventional BCS theory. Here we report experimental discovery of surprising SC up to 310 GPa with T_c above 20 K in wide pressure range from 180 GPa to 240 GPa in titanium. The maximum T_c^{onset} above 26.2 K and zero resistance T_c^{zero} of 21 K are recorded, high values hitherto achieved among element superconductors. The H_{c2}(0) is estimated to be ~32 Tesla with coherence length 32 Å. The results show strong s-d transfer and band dominance, indicating electronic contributions to high T_c in SC. In contrast to the theoretical predictions based on pristine electron-phonon coupling scenario, the findings open a fresh promising avenue for rational design and discovery of high T_c superconductors among simple materials via pressure tuned unconventional mechanism.