Multicomponent odd-parity superconductivity in UAu ₂ at high pressure

Abstract

We report that high-quality single crystals of the hexagonal heavy fermion material uranium diauride (UAu 2 ) become superconducting at pressures above 3.2 GPa, the pressure at which an unusual antiferromagnetic state is suppressed. The antiferromagnetic state hosts a marginal fermi liquid and the pressure evolution of the resistivity within this state is found to be very different from that approaching a standard quantum phase transition. The superconductivity that appears above this transition survives in high magnetic fields with a large critical field for all field directions. The critical field also has an unusual angle dependence suggesting that the superconductivity may have an order parameter with multiple components. An order parameter consistent with these observations is predicted to host half-quantum vortices (HQVs). Such vortices can be topologically entangled and have potential applications in quantum computing.

Enhanced weak superconductivity in trigonal γ-PtBi2

“…In this case, the anisotropy is rather weak but the apparent inversion of coherence length values ξ ab < ξ c is both sizable and puzzling. Such Γ < 1 values have been previously reported in systems like UPd 2 Al 3 thin films (Γ = 0.85) [33], UAu 2 at p = 4.6 GPa (Γ = 0.9) [34], and Lu 2 Fe 3 Si 5 single crystals (Γ = 0.5) [35]. The three of them are special cases: in both hexagonal U-compounds the SC-state emerges in antiferromagnetic (AFM) or nearly-AFM metals, while in the tetragonal Lu-compound 1-dimensional conducting chains are responsible for a larger conductivity along the c−axis, ρ ab /ρ c ∼ 4 for T ≳ T c .…”