Synthesis and thermodynamic properties of superconducting NdPd1-δBi2 (δ∼0.23) single crystals

The interesting phenomena induced by the interaction between local moments and itinerant electrons in 4f compounds have attracted extensive attention for many years. Here, we report the synthesis of a new 4f compound, i.e. NdPd1-δBi2 (δ∼0.23) which is superconducting with a transition temperature Tc around 3.2 K. A comprehensive investigation of the thermodynamic properties suggests NdPd1-δBi2 is also an anti-ferromagnet with the Néel temperature TN ∼4 K. Moreover, its high-temperature paramagnetic state is characterized by an enhanced heat capacity with a Sommerfeld coefficient γ over 300 mJ mol−1 K−2, which presumably results from Nd3+ crystal-electric-field splitting rather than the Kondo effect. In the superconducting state, the suppression of superconductivity with field increasing for H ||c is faster in comparison with H || ab, resulting in a moderate upper critical field anisotropy with Γ=Hc2(0K,‖ab)/Hc2(0K,‖c) ∼2.6. Collectively, NdPd1-δBi2 may serve as an intriguing system to study the interplay among magnetic order, Kondo effect, and superconductivity in 4f compounds. •A new superconducting 4f compound with Tc ∼3.2 K is discovered.•Coexistence of superconductivity and antiferromagnetic order is observed.•The Sommerfeld coefficient γ value is over 300 mJ mol−1 K−2.•The upper critical fields exceed the Pauli limit.