Antiferromagnetism and superconductivity in the half-Heusler semimetal HoPdBi

Orest Pavlosiuk,Dariusz Kaczorowski,Arsen Gukasov,Xavier Fabreges,Piotr Wiśniewski

doi:10.1038/srep18797

Abstract

We observed the coexistence of superconductivity and antiferromagnetic order in the single-crystalline ternary pnictide HoPdBi, a plausible topological semimetal. The compound orders antiferromagnetically at TN = 1.9 K and exhibits superconductivity below Tc = 0.7 K, which was confirmed by magnetic, electrical transport and specific heat measurements. The specific heat shows anomalies corresponding to antiferromagnetic ordering transition and crystalline field effect, but not to superconducting transition. Single-crystal neutron diffraction indicates that the antiferromagnetic structure is characterized by the propagation vector. Temperature variation of the electrical resistivity reveals two parallel conducting channels of semiconducting and metallic character. In weak magnetic fields, the magnetoresistance exhibits weak antilocalization effect, while in strong fields and temperatures below 50 K it is large and negative. At temperatures below 7 K Shubnikov-de Haas oscillations with two frequencies appear in the resistivity. These oscillations have non-trivial Berry phase, which is a distinguished feature of Dirac fermions.

Highlights

More than half a century ago it has been discovered that superconductivity (SC) and antiferromagnetism (AFM) can coexist in one compound, but new reports continue to appear describing this uncommon fusion of properties
Following the method we have applied before for LuPdBi, a nonmagnetic analogue of HoPdBi, we fitted the conductivity plotted versus temperature with a sum of two functions, σm and σs, corresponding to two independent channels of charge transport: metallic- and semiconducting-like, respectively[25]
Our extended specific heat analysis shows that two features, one near 15 K and another below 0.6 K, which can be attributed to crystal electric field (CEF) and nuclear Schottky effect, respectively

Summary

Introduction

More than half a century ago it has been discovered that superconductivity (SC) and antiferromagnetism (AFM) can coexist in one compound, but new reports continue to appear describing this uncommon fusion of properties. This phenomenon can be observed most often in cuprates, iron-based pnictides and chalcogenides, and in a number of heavy fermion materials. Topological semimetals possess ‘topologically protected’ surface states containing Fermi arcs, that were theoretically predicted on the example of pyrochlore iridates[12] and proved experimentally on Cd2As3 single crystals[13] It has recently been proposed, based on ab initio electronic structure calculations, that half-Heusler HoPdBi can be a topological semimetal[4]. Such propagation vector has been determined for another antiferromagnetic half-Heusler compound GdPtBi28

Methods

Results

Conclusion