Anisotropic superconductivity and unusually robust electronic critical field in single crystal La${}_7$Ir${}_3$

Abstract

Polycrystalline La${}_7$Ir${}_3$ is reported to show superconductivity breaking time-reversal symmetry while also having an isotropic $s$-wave gap. Single crystals of this noncentrosymmetric superconductor are highly desirable to understand the nature of the electron pairing mechanism in this system. Here we report the growth of high-quality single crystals of La${}_7$Ir${}_3$ by the Czochralski method. The structural and superconducting properties of these large crystals have been investigated using x-rays, magnetization, resistivity and heat capacity measurements. We observe a clear anisotropy in the lower and upper critical fields for magnetic fields applied parallel and perpendicular to the hexagonal $c$ axis. We also report the presence of a robust electronic critical field, that diverges from the upper critical field derived from heat capacity, which is the hallmark of surface superconductivity.

arXiv comment20 + 5 pages, 6 + 4 figures, 1 + 1 tables. Accepted for publication into Physical Review Materials

References in corpus (26)

• Superconductivity and spin-orbit coupling in non-centrosymmetric materials: a review
• S-wave/spin-triplet order in superconductors without inversion symmetry: Li${}_2$Pd${}_3$B and Li${}_2$Pt${}_3$B
• Evidence for time-reversal symmetry breaking in the non-centrosymmetric superconductor LaNiC${}_2$
• Spin Triplet Superconducting State due to Broken Inversion Symmetry in Li_2Pt_3B
• Theoretical aspects of Andreev spectroscopy and tunneling spectroscopy in non-centrosymmetric superconductors: a topical review
• Observation of Time-Reversal Symmetry Breaking in the Non-Centrosymmetric Superconductor Re6Zr
• Non-unitary triplet pairing in the centrosymmetric superconductor LaNiGa${}_2$
• Time-reversal symmetry breaking in Re-based superconductors
• Time-reversal symmetry breaking in noncentrosymmetric superconductor Re6Hf:further evidence for unconventional behaviour in the alpha-Mn family of materials
• Nodeless superconductivity and time-reversal symmetry breaking in the noncentrosymmetric superconductor Re24Ti5
• Two-gap superconductivity in LaNiGa${}_2$ with non-unitary triplet pairing and even parity gap symmetry
• Time Reversal Symmetry Breaking in noncentrosymmetric superconductor Re6Ti
• Investigations of the superconducting states of noncentrosymmetric LaPdSi3 and LaPtSi3
• Superconducting and normal-state properties of the noncentrosymmetric superconductor Re6Zr
• Time-reversal-symmetry breaking and unconventional pairing in the noncentrosymmetric superconductor La${}_7$Rh${}_3$
• Time-reversal symmetry breaking in the noncentrosymmetric Zr${}_3$Ir superconductor
• Complex superconductivity in the noncentrosymmetric compound Re${}_6$Zr
• Surface superconductivity as the primary cause of broadening of superconducting transition in Nb-films
• Time-reversal symmetry breaking and multigap superconductivity in the noncentrosymmetric superconductor La${}_7$Ni${}_3$
• Fermi surface, possible unconventional fermions, and unusually robust resistive critical fields in the chiral-structured superconductor AuBe
• Upper critical field of the noncentrosymmetric superconductor BiPd
• Multigap Superconductivity in Chiral Noncentrosymmetric TaRh${}_2$B${}_2$
• Investigations of the superconducting ground state of Zr${}_3$Ir: Introducing a new noncentrosymmetric superconductor
• Superconductivity and the upper critical field in the chiral noncentrosymmetric superconductor NbRh${}_2$B${}_2$
• Signatures of the Helical Phase in the Critical Fields at Twin Boundaries of Non-Centrosymmetric Superconductors
• Evidence for the coexistence of time-reversal symmetry breaking and Bardeen-Cooper-Schrieffer-like superconductivity in La${}_7$Pd${}_3$