Rsavs Superconductors: Materials With A Superconducting State That Is Robust Against Large Volume Shrinkage

The transition temperature (T-C) between normal and superconducting states usually exhibits a dramatic increase or decrease with increasing applied pressure. Here we present, in contrast, a type of superconductor that exhibits the exotic feature that T-C is robust against large volume shrinkages (RSAVS, so naming them "RSAVS superconductors") induced by applied pressure. Extraordinarily, our previous studies found that the T-C in the two 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. Here, 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 occurs universally in a certain kind of superconductor, composed of only transition metal elements, with a body-centered cubic lattice. Our electronic structure calculations indicate that in the RSAVS state the contribution of the degenerate d(x2-y2) and d(z2) orbital electrons remains almost unchanged at the Fermi level, suggesting that these are the electrons that may play a crucial role in stabilizing the T-C in the RSAVS state. We preliminarily analyzed the reasonability and validity of this suggestion by the Homes law.