Sep 20 2022Reviewed by Mila Perera
Element superconductors (SCs) are vital for potential applications or for superconducting mechanism studies due to their single composition. Element SC, however, often exhibits a very low transition temperature (Tc), which is usually less than 10K.
Lately, the team of Prof. Changqing Jin at IOPCAS found Ti metal to be superconductive with Tc over 26K at high pressures — which is the record high for element superconductors until today.
They discovered that Ti metal remains superconductive with Tc over 20 K in a broad pressure range of 150–310 GPa, while the highest 26.2 K Tc is reached at 248 GPa. The superconductivity of all identified superconductors can sustain the highest pressure of 310 GPa.
They showed that 4s orbital derived bands are transferred up to Fermi level through pressure that tends to cause the density of state nearby Fermi level to be regulated at high pressures by 3d electrons.
The high temperature superconductivity is proposed to be closely related to the 3d electrons that usually demonstrate electron correlation interaction.
Changqing Jin, Professor, Institute of Physics, Chinese Academy of Sciences
They also estimated the upper critical magnetic field. “The Hc2 is ~30 Tesla that corresponds to a GL coherent length ~32 Å,” stated Prof. Xiancheng Wang, a co-author of the study. Promising for prospective applications in extreme surroundings, at high pressure, both Tc and upper critical magnetic field of Ti SC are twice as large as those of extensively used superconducting NbTi alloy (Tc~9.6 K，Hc2~ 15 Tesla).
It can be seen from the discovery that high Tc SC can be attained in elemental compounds or metals with simple elements through the combination of electron-phonon coupling and electron correlations. These simple components are more suitable and adaptive for applications in varied and challenging implementation situations.
In oceans, space, and deep earth environments, the titanium (Ti) metal has been widely used owing to its exceptional properties of high strength, lightweight, and resistance to corrosion. Ti’s other outstanding trait is the record high Tc superconductivity at high pressure. At extreme conductions, it can be of great use.
The study was funded by NSF, MOST, and CAS of China via research projects.
Zhang, C., et al. (2022) Record high Tc element superconductivity achieved in titanium. Nature Communications. doi.org/10.1038/s41467-022-33077-3.