Theory of nodal s ± -wave pairing symmetry in the Pu-based 115 superconductor family.

Jian-Xin Zhu,Matthias J Graf,Tanmoy Das

doi:10.1038/srep08632

Jian-Xin Zhu, Matthias J Graf + Show 1 more

Open Access

https://doi.org/10.1038/srep08632

Copy DOI

Abstract

The spin-fluctuation mechanism of superconductivity usually results in the presence of gapless or nodal quasiparticle states in the excitation spectrum. Nodal quasiparticle states are well established in copper-oxide, and heavy-fermion superconductors, but not in iron-based superconductors. Here, we study the pairing symmetry and mechanism of a new class of plutonium-based high-Tc superconductors and predict the presence of a nodal s+− wave pairing symmetry in this family. Starting from a density-functional theory (DFT) based electronic structure calculation we predict several three-dimensional (3D) Fermi surfaces in this 115 superconductor family. We identify the dominant Fermi surface “hot-spots” in the inter-band scattering channel, which are aligned along the wavevector Q = (π, π, π), where degeneracy could induce sign-reversal of the pairing symmetry. Our calculation demonstrates that the s+− wave pairing strength is stronger than the previously thought d-wave pairing; and more importantly, this pairing state allows for the existence of nodal quasiparticles. Finally, we predict the shape of the momentum- and energy-dependent magnetic resonance spectrum for the identification of this pairing symmetry.

Highlights

The spin-fluctuation mechanism of superconductivity usually results in the presence of gapless or nodal quasiparticle states in the excitation spectrum
We begin by evaluating the nature of enhanced Fermi surface (FS) scattering or hot-spots, and the electronic fingerprints of s6, and dx2{y2 -wave pairing symmetries for three known Pu-115 superconductors PuCoIn5 (Tc 5 2.5 K)[21], PuCoGa5 (Tc 5 18.5 K)[14], and PuRhGa5 (Tc 5 8 K)[22]
The location of the maximum of xðqÞ~ n,m xnmðq, 0Þ is primarily in the vicinity of Q, (p, p, p), with additional weights spread all along qz. This suggests that the dominant FS instability occurs between the FSs separated by Q in the Brillouin zone. For this value of Q, we identify the locations of the electronic hot-spots or the highest joint-density of states (JDOS), which satisfy Q~kni {kmf, where kni and kmf are the Fermi momenta in the initial and final states of bands n and m, respectively

Summary

Introduction

The spin-fluctuation mechanism of superconductivity usually results in the presence of gapless or nodal quasiparticle states in the excitation spectrum. Theory of nodal s6-wave pairing symmetry in the Pu-based 115 superconductor family

Results

Conclusion