Experimental signatures of nodeless multiband superconductivity in a hbox {2H-Pd}_{0.08} hbox {TaSe}_2 single crystal

Chanhee Kim,Jeehoon Kim,Byung-Gu Jeon,Yeahan Sur,Byeong Hun Min,Dilip Bhoi,Kee Hoon Kim,Dirk Wulferding

doi:10.1038/s41598-021-92709-8

Abstract

In order to understand the superconducting gap nature of a hbox {2H-Pd}_{0.08} hbox {TaSe}_2 single crystal with T_{c} = 3.13 text { K}, in-plane thermal conductivity kappa , in-plane London penetration depth lambda _{text {L}}, and the upper critical fields H_{c2} have been investigated. At zero magnetic field, it is found that no residual linear term kappa _{0}/T exists and lambda _{text {L}} follows a power-law T^n (T: temperature) with n = 2.66 at T le frac{1}{3}T_c, supporting nodeless superconductivity. Moreover, the magnetic-field dependence of kappa _{0}/T clearly shows a shoulder-like feature at a low field region. The temperature dependent H_{c2} curves for both in-plane and out-of-plane field directions exhibit clear upward curvatures near T_c, consistent with the shape predicted by the two-band theory and the anisotropy ratio between the H_{c2}(T) curves exhibits strong temperature-dependence. All these results coherently suggest that hbox {2H-Pd}_{0.08} hbox {TaSe}_2 is a nodeless, multiband superconductor.

Highlights

Experimental signatures for the Multiband superconductivity (MBSC) have been observed in iron-based superconductors[6], in which sign-changing, nodeless gaps exhibit as many as five different electron and hole p ockets[7]
As the superconductivity often arises within the CDW ground state, where complex Fermi surfaces composed of multiple 4d or 5d bands and ligand p bands are involved[14], there is a good possibility of observing MBSC
The study on the MBSC has been limitedly performed in e.g., Nb-based TMDs with relatively high-Tc above 6 K; for example, both 2H-NbS2 (T c ≃ 6.1 K ) and 2H-NbSe2 (T c ≃ 7.2 K ) were found to host nodeless multiband superconductivity based on various experimental probes such as Cp15,16, κ17, London penetration depth ( L)[18,19], and angle-resolved photoemission spectroscopy (ARPES)[14]

Summary

Introduction

The temperature dependent Hc2 curves for both in-plane and out-of-plane field directions exhibit clear upward curvatures near Tc , consistent with the shape predicted by the two-band theory and the anisotropy ratio between the Hc2(T) curves exhibits strong temperature-dependence All these results coherently suggest that 2H-Pd0.08TaSe2 is a nodeless, multiband superconductor. The study on the MBSC has been limitedly performed in e.g., Nb-based TMDs with relatively high-Tc above 6 K; for example, both 2H-NbS2 (T c ≃ 6.1 K ) and 2H-NbSe2 (T c ≃ 7.2 K ) were found to host nodeless multiband superconductivity based on various experimental probes such as Cp15,16, κ17, London penetration depth ( L)[18,19], and angle-resolved photoemission spectroscopy (ARPES)[14]. To fully elucidate the true nature of superconductivity, systematic experimental studies are required in each material system

Methods

Results

Conclusion