Superconductivity and magnetic order in ErPdBi (Vol. 45 No. 1)

Superconducting (SC) and magnetic (AFM) phase diagram of ErPdBi. Inset: Half-Heusler crystal structure.

Half-Heusler compounds attract ample attention because of their flexible electronic structure. A new electronic state in this respect is the topological insulator, where the interior of the material is insulating, while the surface states are conducting. Surprisingly some of the topological half-Heusler compounds become superconducting at low temperatures. Topological superconductors are predicted to have a fully gapped unconventional pairing state in the interior, while the non-trivial topology gives rise to Majorana fermion states at the edge of the sample. The further interplay with magnetic order may lead to exotic superconducting phases.

In the paper the discovery is reported of a new candidate for topological superconductivity: ErPdBi. Magnetic and transport measurements demonstrate superconductivity at Tc = 1.22 K, and, moreover, magnetic order at TN= 1.06 K. Since TN ≈ Tc the interaction of superconductivity and magnetic order is expected to give rise to a complex ground state. Electronic structure calculations reveal a topologically non-trivial band inversion. Accordingly, ErPdBi is advocated as a novel, unique platform to study the interplay of topological states, superconductivity and magnetic order.

Y. Pan, A.M. Nikitin, T.V. Bay, Y.K. Huang, C. Paulsen, B.H. Yan and A. de Visser, "Superconductivity in the noncentrosymmetric half-Heusler compound ErPdBi", EPL, 104, 27001 (2013).