Element superconductors are important either for superconducting mechanism studies or for potential applications because of the single composition. However element superconductor (SC) usually show very low transition temperature (Tc) typically below 10K. Recently Prof. Changqing Jin’s team at IOPCAS discovered Ti metal to be superconductive with Tc above 26K at high pressures: the record high for element superconductors so far.
They found that Ti metal keeps superconductive with Tc above 20 K in a wide pressure range from 150 to 310 GPa while maximum 26.2 K Tc is achieved at 248 GPa. The 310 GPa is also the highest pressure that superconductivity can sustain for all known superconductors. They indicated that 4s orbital derived bands are moved up to Fermi level by pressure that causes the density of state near Fermi level is controlled by 3d electrons at high pressures. “The high temperature superconductivity is proposed to be closely related to the 3d electrons that usually demonstrate electron correlation interaction.”addressed Changqing JIN. They also estimated the upper critical magnetic field “the Hc2 is ~30 Tesla that corresponds to a GL coherent length ~32 Å.” commented Prof. Xiancheng Wang who is the coauthor of the paper. Both Tc and upper critical magnetic field of Ti SC at high pressure are notably doubled higher than those of widely used superconducting NbTi alloy (Tc~9.6 K，Hc2~ 15 Tesla), promising for potential applications at extreme environments. From the discovery it seems high Tc SC can be achieved in elemental metals or compounds with simple components via the joint of electron phonon coupling and electron correlations, and such simple materials are more adaptive and suitable for applications in diverse and demanding implementation settings. The titanium (Ti) metal has been widely used in aerospace, ocean, deep earth environments due to its unique properties of light weight, high strength and corrosion resistance. The record high Tc superconductivity at high pressure marks Ti one more excellent trait. It can be of potential applications at extreme conductions.
The work has been published in Nature Communication 13, 5411(2022) recently. The work is supported by NSF, MOST and CAS of China through research projects.