Two-band superconductivity with unconventional pairing symmetry in HfV2Ga4

Abstract

In this letter, we have examined the superconducting ground state of the HfV2Ga4 compound using resistivity, magnetization, zero-field (ZF) and transverse-field (TF) muon-spin relaxation and rotation (µSR) measurements. Resistivity and magnetization unveil the onset of bulk superconductivity with Tc ∼ 3.9 K, while TF-µSR measurements show that the temperature dependence of the superfluid density is well described by a nodal two-gap s+d-wave order parameter model. In addition, ZF muon relaxation rate increases with decreasing temperature below 4.6 K, indicating the presence of weak spin fluctuations. These observations suggest an unconventional multiband nature of the superconductivity possibly arising from the distinct d-bands of V and Hf ions with spin fluctuations playing an important role. To better understand these findings, we carry out firstprinciples electronic-structure calculations, further highlighting that the Fermi surface consists of multiple disconnected sheets with very different orbital weights and spin-orbit coupling, bridging the way for a nodal multiband superconductivity scenario. In this vein, therefore, HfV2Ga4-family stands out as an open avenue to novel unexplored unconventional superconducting compounds, such as ScV2Ga4 and ZrV2Ga4, and other many rare earths based materials.

Evidence for multiband superconductivity and charge density waves in Ni-doped ZrTe$_2$

“…We can observe a clear predominance of Zr-d orbitals in the con-duction, electron band (β 1 pocket) and a majority contribution of Te-p orbitals in valence, hole bands (α 1 and α 2 pockets). The disconnected multiband nature with very distinct orbital projections, Fermi velocities, and nesting vectors support two-band superconductivity conjecture in this system [56,68,[71][72][73][74][75], consistently with the experimental findings. In fact, the different band Fermi velocities of ZrTe 2 favors the emergence of such unconventional superconducting magnetic properties due to the presence of multiple condensates with dissimilar compet-ing characteristic lenghts [76].…”

Probing nodeless superconductivity in LaMSi ( M=Ni , Pt) using muon-spin rotation and relaxation

“…A decrease in fluctuation frequency of electronic moments as temperature decreases may cause to increase. Similar behavior is observed in a number of superconductors [51][52][53]. However, the exact nature and source of this behavior is still unknown and therefore requires further investigation.…”

Possible multiband superconductivity in the quaternary carbide YRe2SiC

“…In fact, the small contributions of Y-4d and Si-3p wavefunctions in the Fermi surface is consistent with the smaller second anomaly found in heat capacity measurements [34,53]. The topography of the Fermi surface also favors nesting-induced instabilities in both spin and charge susceptibilities, possibly leading the system on the verge of unconventional superconductivity [52][53][54][55], as suggested by the linear dependence of Hc1 with temperature.…”