Strongly correlated and strongly coupled s-wave superconductivity of the high entropy alloy Ta1/6Nb2/6Hf1/6Zr1/6Ti1/6 compound

Gareoung Kim, Min Ho Lee, Jae Hyun Yun, Pooja Rawat, Soon Gil Jung, Woongjin Choi, Tae Soo You, Sung Jin Kim, Jong Soo Rhyee

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High entropy alloy (HEA) is a random mixture of multiple elements stabilized by high mixing entropy. We synthesized a Ta1/6Nb2/6Hf1/6Zr1/6Ti1/6 bulk HEA compound as a body-centered cubic structure with lattice parameter a = 3.38 Å based on arc melting. From the electronic and magnetic property measurements, we obtained the superconducting properties such as electron-phonon coupling constant λel-ph, electron-phonon potential Vel-ph, density of states at the Fermi level D(EF), superconducting energy gap 2Δ(0)/kBTc, upper-critical field Hc2(0), coherence length ξ, and critical current density Jc. The compound showed a superconducting transition at Tc = 7.85 K. The compound has relatively sizeable specific heat jump (ΔC/γTc), high effective mass of carrier (29 me), and high Kadowaki-Woods ratio (A/γ2, which plays an important role in the heavy Fermi compounds), indicating that it resides within the strongly coupled s-wave superconductor within a dirty limit. Its vortex pinning force is described by the Dew-Huges double exponential pinning model, implying that there are two types of pinning mechanisms. The possible coexistence of strongly correlated behavior in s-wave superconductivity in HEA compounds is noteworthy because many of the strongly correlated superconductors, such as heavy-fermion and high Tc cuprate superconductors, have nodal gap symmetry. The HEA compound suggests exploiting different types of superconductivity with the current strongly correlated superconductors as well as metallic superconductors.

Original languageEnglish
Pages (from-to)250-256
Number of pages7
JournalActa Materialia
StatePublished - Mar 2020


  • High entropy alloy
  • S-wave
  • Strongly correlated system
  • Superconductor


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