RSAVS superconductors: materials with a superconducting state that is robust against large volume shrinkage

Abstract

TThe transition temperature (TC) between normal and superconducting states usually exhibits a dramatic increase or decrease with increasing applied pressure. Here we present, in contrast, a new kind of superconductor that exhibits the exotic feature that TC is robust against large volume shrinkages induced by applied pressure (here naming them as "RSAVS superconductors"). Extraordinarily, the TC in these materials stays almost constant over a large pressure range, e.g. over 136 GPa in the (TaNb)0.67(HfZrTi)0.33 high entropy alloy and 141 GPa in the NbTi commercial alloy. We show that the RSAVS behavior also exists in another high entropy alloy (ScZrNbTa)0.6(RhPd)0.4, and in superconducting elemental Ta and Nb, indicating that this behavior, which has never previously been identified or predicted by theory, occurs universally in some conventional superconductors. Our electronic structure calculations indicate that although the electronic density of state (DOS) at the Fermi level in the RSAVS state is dominated by the electrons from the degenerate dxy, dxz and dyz orbitals, these electrons decrease in influence with increasing pressure. In contrast, however, the contribution of the degenerate dx2-y2 and dz2 orbital electrons remains almost unchanged at the Fermi level, suggesting that these are the electrons that may play a crucial role in stabilizing the TC in the RSAVS state.

12 pages, 4 figures

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Cited by in corpus (5)

• Record high $T_{\mathrm{c}}$ and robust superconductivity in transition metal $\delta$-Ti phase at megabar pressure
• Fishtail effect and the vortex phase diagram of high-entropy alloy superconductor
• First-principles study of the robust superconducting state of NbTi alloys under ultrahigh pressures
• Local distortions of the crystal structure and their influence on the electronic structure and superconductivity of the high-entropy alloy (TaNb)0.67(HfZrTi)0.33
• Comparative studies on unconventional superconductivity in Cr${}_3$Ru compounds with bcc and A15 structures