Insights on unconventional superconductivity in HfV$_2$Ga$_4$ and ScV$_2$Ga$_4$ from first principles electronic structure calculations

TL;DR

This study uses first-principles calculations to analyze the electronic structure of HfV₂Ga₄, revealing its multiband superconductivity and predicting a critical temperature close to experimental values, with implications for related compounds like ScV₂Ga₄.

Contribution

The paper provides detailed electronic structure insights into HfV₂Ga₄ and predicts its superconducting properties, also proposing the potential of higher $T_c$ in ScV₂Ga₄ based on similar electronic features.

Findings

Density of states at Fermi level mainly V–$d$ states.

Predicted $T_c$ of 3.9 K matches experimental 4.1 K.

Evidence of multiband superconductivity from band analysis.

Abstract

The HfV$_2$Ga$_4$ compound was recently reported to exhibit unusual bulk superconducting properties, with the possibility of multiband behavior. To gain insight into its properties, we performed ab-initio electronic structure calculations based on the Density Functional Theory (DFT). Our results show that the density of states at the Fermi energy is mainly composed by V--$d$ states. The McMillan formula predicts a superconducting critical temperature ($T_{c}$) of approximately $3.9\,$K, in excellent agreement with the experimental value at $4.1\,$K, indicating that superconductivity in this new compound may be explained by the electron-phonon mechanism. Calculated valence charge density maps clearly show directional bonding between Hf and V atoms with 1D highly populated V-chains, and some ionic character between Hf--Ga and V--Ga bonds. Finally, we have shown that there are electrons occupying two distinct bands at the Fermi level, with different characters, which supports experimental indications of possible multiband superconductivity. Based on the results, we propose the study of a related compound, ScV$_2$Ga$_4$, showing that it has similar electronic properties, but probably with a higher $T_c$ than HfV$_2$Ga$_4$.