  X-ray powder diffraction, electrical resistivity, magnetization, and
thermodynamic measurements were conducted to investigate the structure and
superconducting properties of TiHfNbTaMo, a novel high-entropy alloy possessing
a valence electron count (VEC) of 4.8. The TiHfNbTaMo HEA was discovered to
have a body-centered cubic structure and a microscopically homogeneous
distribution of the constituent elements. This material shows type-II
superconductivity with Tc = 3.42 K, lower critical field with 22.8 mT, and
upper critical field with 3.95 T. Low-temperature specific heat measurements
show that the alloy is a conventional s-wave type with a moderately coupled
superconductor. First-principles calculations show that the density of states
(DOS) of the TiHfNbTaMo alloy is dominated by hybrid d orbitals of these five
metal elements. Additionally, the TiHfNbTaMo HEA exhibits three van Hove
singularities. Furthermore, the VEC and the composition of the elements
(especially the Nb elemental content) affect the Tc of the bcc-type HEA.
