Pressure-induced superconductivity and modification of Fermi surface in type-II Weyl semimetal NbIrTe4

Qing-Ge Mu,Horst Borrmann,Claudia Felser,Yan Sun,Walter Schnelle,Sergey Medvedev,Feng-Ren Fan

doi:10.1038/s41535-021-00357-y

Qing-Ge Mu, Horst Borrmann + Show 5 more

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https://doi.org/10.1038/s41535-021-00357-y

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Abstract

Weyl semimetals (WSMs) hosting Weyl points (WPs) with different chiralities attract great interest as an object to study chirality-related physical properties, topological phase transitions, and topological superconductivity. Quantum oscillation measurements and theoretical calculations imply that the type-II WPs in NbIrTe4 are robust against the shift of chemical potential making it a good material for pressure studies on topological properties. Here we report the results of electrical transport property measurements and Raman spectroscopy studies under pressures up to 65.5 GPa accompanied by theoretical electronic structure calculations. Hall resistivity data reveal an electronic transition indicated by a change of the charge carrier from multiband character to hole-type at ~12 GPa, in agreement with the calculated Fermi surface. An onset of superconducting transition is observed at pressures above 39 GPa, with critical temperature increasing as pressure increases. Moreover, theoretical calculations indicate that WPs persist up to highly reduced unit cell volume (−17%), manifesting that NbIrTe4 is a candidate of topological superconductor.

Highlights

Weyl semimetals (WSMs) have attracted extensive attention in condensed matter physics[1,2,3,4]
Hall measurements reveal that samples of NbIrTe4 can adopt different Fermi levels, indicating that its Fermi surface is very sensitive to changes of the chemical potential, while the Weyl points (WPs) persist against the shift of Fermi level as suggested from calculations[34,35,36]
NbIrTe4 crystalizes in an orthorhombic crystal structure without inversion symmetry and exhibits a characteristic layer stacking along the c-axis (Fig. 1a)[32]

Summary

INTRODUCTION

Weyl semimetals (WSMs) have attracted extensive attention in condensed matter physics[1,2,3,4]. Hall measurements reveal that samples of NbIrTe4 can adopt different Fermi levels, indicating that its Fermi surface is very sensitive to changes of the chemical potential, while the WPs persist against the shift of Fermi level as suggested from calculations[34,35,36] These features make NbIrTe4 a good platform to study the effect of pressure on its topological properties. We report the effects of high pressure on electrical transport properties and crystal structure of the type-II WSM NbIrTe4 under external pressures up to 65.5 GPa. Hall effect measurements reveal that the Fermi surface changes from a multiband character to hole dominated at ~12 GPa. Superconductivity is detected at pressures above 39 GPa, and the onset critical temperature Tc increases monotonically with further compression. The observed pressure-induced superconductivity in NbIrTe4 is in good agreement with the recent results for the isostructural compound TaIrTe431, demonstrating that the superconductivity under compression is an intrinsic property of this class of compounds

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